Like AK, Desert Rats is notable for what is missing: Shermans, Deacons, portees, 2pdr anti-tank guns, Priests, and variety in armoured car choices. It too has a dubious inclusion in the form of the 17/25pdr anti-tank gun. My guess is that the Tiger was included in AK because Tiger, and the 17/25pdr then had to be added to try and restore game balance. But once you subtract those anachronisms, in my opinion the two books are actually a very good representation of generic forces from British and German armoured divisions in July 1942.
Seeing what is in Desert Rats, the thinking behind AK, and mid-war in general, has started to become clear. It's now obvious that V4 is a total reboot of the system as Team Yankee WW2, targeted at those who have never played FOW, because with the completion of the V3 lists for the entire war there is now little money in existing customers. The mid-war models will all be sold as platoon boxed sets, and the scope of each list will be set by production capacity and release schedules for those boxes.
In a world where V1 to V3 didn't exist, V4 would be huge. A (presumably) tight set of fast-play rules that (hopefully) look and feel like a WW2 game, nice miniatures conveniently packaged, the promise of expansion into other nations and list types, an arms race between gamers as new units were purchased. But that those earlier versions have been and gone, that experience is exactly what playing FOW was like in its heyday, and the people most likely to be attracted by WW2 gaming in 15mm already have been there, done that, and many of them have drifted away. Since they have multiple armies across multiple eras sitting in boxes, they might try a game or two of V4 out of curiosity, but they won't stick with it because the lack of variety in the initial releases. It will be a couple of years before the system is mature enough to run a native V4 tournament, and by the time the game gets to that point those veteran players may not be able to be enticed back.
So where will the target audience, these new players that V4 is going to attract, come from? You can't accidentally find FOW in New Zealand any more. I believe there are only three brick-and-mortar retailers of FOW left in the country, and the nearest of those is a seven hour drive from my hometown, which just happens to be the capital and third-largest city. Without the product having a ground presence, people will only find out about the game by seeing it played, either at conventions or clubs, and that requires the aforementioned veterans to be playing it. There may be a small amount of growth from second generation players who have access to their dad's old miniatures, who will try it and may end up getting some of their friends interested, but that's it. But in all honesty, I can only see further decline for FOW in New Zealand.
The unknown in all of this is the EW/LW conversion, with the questions being how it plays, how the V3 lists balance out under the new rules, and how long it will be before those eras are remade in mid-war's image? And most importantly, will it be enough to at least keep people playing the game while MW sorts itself out?