By Professor Michael Clarke, Visiting Professor of Defence Studies at King's College London and former Director-General at the Royal United Services Institute (RUSI).
Transforming the Armed Forces always involves a mixture of pain and promises – giving up some capabilities and customs to create the space and the mindset for some new ones.
We can expect the Defence White Paper on Monday to embody a heady mixture of both pain and promise.
The Government will be anxious to show that its long-term promises are just as real as the short-term pain is bound to be.
Retiring the 'sunset' capabilities in favour of more rapid investment in 'sunrise' technologies has been an easy slogan while the Integrated Review was in the mixer.
But this week we move towards the business end of the matter, when we see what the Ministry of Defence has put into print.
On the basis of what we already know, what sort of pain and promise are each of the armed services likely to face?
All three of them are on a journey to the same destination in 2030; integrating the five domains of warfare – air, land, sea, space and cyber – and in the right shape for the digitised world.
But all three services are on a journey of their own and at a different pace.
They hope to arrive together at the end of the decade in some sort of good order.
The Royal Air Force
The RAF's pain is that it will be losing some platforms.
Its fleet of 14 transport C-130Js will likely be withdrawn, its Sentinel and Islander fleet may be taken out of service in 2022, the new Wedgetail surveillance aircraft fleet may be cut from five to three, creating a clear gap, at least for a while.
The Royal Squadron (32) will lose its own aircraft and have to lease civilian aircraft.
And most noteworthy, it seems as if 24 of the older Typhoon aircraft may be retired early and the projected number of new F-35 Lightnings, due to be procured, may be either severely curtailed or else left in limbo for a while.
The confirmed number of F-35s for both the Navy and the RAF could be as low as 48, compared to the increasingly mythical target of 138, which would cover the Navy's carrier requirement but leave the RAF in severe straits.
More likely, however, is some conditional wiggle room will be indicated from a definite 48 up to something between 60 and 76, although perhaps in an unspecified timescale.
On the promises side of the ledger, the RAF will get the scope to run its ASTRA programme, launched in 2020 to up-skill and reorganise the force, investing in new ISTAR technologies and many different types of robotics.
The centrepiece is undoubtedly the Tempest 'Future Combat Air System' which will probably be a mixture of crewed and robotic aircraft.
By 2040, one vision for the RAF is that it will operate a modest number of combat aircraft which then work with, or direct, a great many drones and robot airframes in roughly a 20/80 ratio.
The RAF's bigger aircraft numbers might then lie in the transport and other support fleets. Not least, the RAF will be running Space Command which should integrate combat systems across all five domains of warfare.
For the RAF the pain will be immediate but the promise is not far behind.
With a mix of Typhoon and (some) Lightening combat jets and the investments in the ASTRA and Tempest programmes having a good chance of paying off, the force could be arriving in the right shape by the end of the decade.
By then, the RAF would be doing a lot of very new things, but that journey of transformation is mapped out.
The Royal Navy
For many domestic reasons, it has been a major boost to British shipbuilding.
Very soon, British shipyards will be constructing or developing no fewer than eight different classes of ships for the Navy.
Three new types of frigates, two new types of submarines, three different classes of support vessels, solid support ships, multi-role support ships and ocean surveillance.
There is also expected to be a follow-on at the end of the Astute-class submarine programme, if only to help protect undersea cables in the Atlantic.
The pain for the Royal Navy is more a problem of managing the inevitable dip in the numbers of the escort fleet, and possibly in submarines, around the middle of the decade.
The escort fleet will fall from 19 to 17, or possibly fewer, before rising eventually to 24 vessels.
Given the demands that aircraft carriers make on escort numbers, this could be more challenging than it sounds. And the Navy will still have to marshal its resources very carefully and up-skill and reorganise its personnel.
Unlike the other two services, the Navy will look more traditional over the next decade, with ships going about their business as we might expect.
By 2025, the Navy will finally take on the shape with the platforms and equipment it had planned for in 2010.
But this may be a mixed blessing.
The Integrated Review implies that it could be mightily stretched in being given so many roles to perform.
Not least, the creation of the RAF's Space Command and what one senior officer described as 'the geometry of orbital space' raises intriguing questions about the global locations of outposts such as Cyprus, Gibraltar, Diego Garcia, Ascension Island, the Falklands or the Pitcairn Islands.
In the digital age, the Navy might find itself stretched to perform many traditional roles while still trying to adjust to new parameters of maritime conflict and future warfare.
It is no secret that the Army will feel the most pain in the immediate future and will also have the most circuitous journey to reach 2030 in a genuinely transformed state.
The expectation is that the Army will lose all its 750 Warrior fighting vehicles while it acquires just under 600 of the, not universally popular, Ajax armoured fighting vehicles and 500, very long-awaited Boxer mechanised infantry vehicles.
Its tank fleet will be rationalised from more than 220 Challenger 2s to 150 upgraded 'Challenger 3' tanks.
Its 1970s vintage howitzers will probably be scrapped outright, and its heavy artillery, the AS-90 and Multiple Launch Rocket System, will likely go out of service quite early to make way for attack drones and long-range rockets.
The shape of the Army's combat division will probably change to include two rather than four armoured brigades.
Official troop numbers are expected to fall to 72,500 and then 70,000 by 2030.
About 23 battalions, or battalion-sized units, are expected to be affected, abolished, merged, or re-roled.
Four battalions have already been cut to half-size and given different roles as 'Specialised Infantry Battalions', and this may continue with even smaller battalions working in niche areas and not necessarily in, or even close to, the traditional combat zone.
In embracing the need to fight 'deep' in the operational area, as well as up close and personal at some later stage, the Army not only has to take on much greater data management, surveillance, reconnaissance and intelligence capacities, alongside its deep-strike weapons.
It has also got to integrate these capabilities low down into its own units.
Having new battle-winning technologies only at headquarters misses the point of them.
Different ways of competing and fighting with the tools of the digital age have to run through the Field Army like a new lifeblood.
Every unit, in some part, has to be its own 77th Brigade.
That is a tall order for any organisation, and unlike the Navy and the RAF, the Army's new heavy metal has been promised, but is still to arrive.
When it does, there will be many new 'sunrise' technologies and new ground force weapon systems, deep strike and all that goes with it, to mesh with the new equipment.
Army chiefs are determined to take it on, as one would expect, but they know that this review puts them on a long and winding road to 2030.
None of the 'pain and promise' equation, of course, addresses the strategy that all this is designed to deliver.
Assessing the viability of that, will require careful comparison between last week's document and the one we will see on Monday.
But none of it will make much sense unless all three services are closing in on 2030 and their own transformations are converging.
Only that will create the synergistic impact that small military forces must have if they are given 'Global Britain' roles to perform.
Michael Clarke is Visiting Professor of Defence Studies at King's College London and the former Director-General at the Royal United Services Institute until 2015.