Plutonium

I don't think that's necessary.

Apart from another client, I would do nothing more than hinder and delay your other projects (iw5 and t6).

It would require more work and time, remember they do it for free.

Maybe it's possible, but I don't think it's something you do overnight.

Apart from that there are already customers for BO1 and MW2 as commented.

You should also keep in mind that adding another game or COD to the project would probably cause more people to disperse, affecting the MW3/BO2 servers, leaving them almost empty.