Definitely agree the RTS side should come first, but I think if you look at Project Reality then there is definitely room for infantry combat. The most important thing to avoid lone-wolfing is streamlined communication. The way PR does this is Mumble tied to the .exe and an intuitive squad menu system. I believe this is the key to getting players that aren't in a clan to cooperate, TS doesn't cut it.
If you bring in Receiver-style weapon mechanics, a manual on weapon operation & how to be a good boy and not piss off your squad leader you'd get people taking it seriously.