It's funny. For a long time, I thought DCS = CA, pretty much. (* Also for the 6 years that passed, it's the reason why it stayed on my radar. (It's really that long - I even looked up our 10 page thread on the regular gaming forum.)
Some recent events made DCS very relevant again so I added CA + Gazelle to my collection. After 3 missions of CA, the impressions are a bit underwhelming - capricious at worst, maybe somewhat tedious at best. Feels like it violates several core principles of good RTS design. Then again there are some positives, eg. I like the simulation feel to the battle. Gazelle on the other hand is fun and interesting in a way that's different from the rest.
That 40 bucks feels really steep for CA. 15 years ago it could have been an interesting RTS game (with some polish). But it's really hard to evaluate except in a very subjective way without knowing what is ED's strategy and goals with the functionality. I can only hope that the price is a signal to the gaming community that something big is coming in CA 2.0.
What we can wish from CA depends much on the resources available. Making a FPS infantry shooter would be a whole new project, and TBH a bit of an odd choice. Parallels to RTS/RTT and WarGame is solid thinking - basically the root of things is already there in current CA. Making an FPS armor (mechanized) game could be a possibility but would require changes to maps, the engine, much new game design and so on; it could have benefits for air warfare too. The problem with all this is that there is competition; in some genres there is LOTS of competition, which on top typically has several years of head start. The key is to ask what kind of value CA provides to players and who are the target group of this module (ground warfare enthusiasts on Steam? high flyer lead customers who will brush $40 under Miscellaneous in their gaming budget?). There are already some very good examples how you can seamlessly integrate different gameplay elements, study those and you're starting to understand what you are trying to do. Make it all rewarding, meaningful and integrate well with the rest of DCS -> profit.
Another possibility would be to work on other similar extensions to the game and engine. For example an operational/strategic level campaign engine for full base management, supply, logistics...
Often the best game companies seem to be really good in some (unique) core areas. They focus on them while running for a number of other goals as well. Sometimes they are something necessary for a game experience that is an entertaining whole - often they are not something to write home about or even something which everybody involved wants to forget as quickly as possible.
(* Several reasons why that might have happened, eg.: