It'll be interesting to see it the TT V6 makes it into the next Camaro. My first instinct would be, no, it won't because TT V6 is going to be an expensive engine to build and the V8 offers similar performance for less money.
On the other hand, economies of scale would suggest that GM will try to recoup it investment in this TT V6 by offering it in more than just the CTS. Obviously, the ATS and the XTS are possible candidates for offering the engine. Some theoretical Alpha-platform Buick (Grand National?) might also be a possibility. And, then, of course, there's the Camaro. We'll see...