I don't think we have enough details to know what is going to happen with a Flames of War v4. The fact of the matter is we know only three things:
1. They are changing the points to 100 scale from 1500 scale
2. We are getting a v4
3. They are starting with a mid war update w/ new plastics
I for one remain optimistic. Every time a new version of rules comes out there's a lot of skepticism, but Battlefront has had good rules in v1 of Flames, and it's only gotten better with each release. Current trends point to v4 being another step up. Honestly I can't think of any rules in Team Yankee that would not make Flames of War better for example:
1. You can still hit things needing a 7. You have to roll to hit on a six, and then reroll to hit on a 5+, similarly you can roll to hit on an 8, need to roll two sixes.
2. Every gun has a Moving and stationary firing speed. Makes for more depth as now you can have different guns fire at different rate of fire on the move instead of everything gets halved.
3. Breakthrough Guns (called Brutal in TY) require infantry to reroll their successful saves instead of eliminating their saves altogether
4. Artillery - You can call down artillery anywhere on the board, including smoke bombardments on your own troops in order to help them advance, or take cover
5. Its much shorter, Team Yankee's rule book shortens down the rules from almost 300 pages in Flames of War, to around 40 pages for Team Yankee. This is a huge relief to new players, as they can self-teach themselves instead of having to rely on other to show them the ropes. I've had several people turned away from Flames of War because of the large complex rule set.
So overall I don't see anything in the Team Yankee rules that I dislike, and many things could really improve our current Flames of War rule set. Team Yankee does not lose the tactical depth of Flames of War, but it does reduce the complexity that is a barrier to new players. In short Team Yankee is easier to learn, harder to master.
Note: I am also of the opinion that the change of how the points work is simply ridiculous, I seriously hope they change their minds on this point.