I think that a trampoline decorator is an acceptable substitute for new syntax that indicates that a call is a tail call and should be optimized as such.
I'm still thinking about whether or not such a syntax is an acceptable replacement for real TCO. Part of me says that explicit is better than implicit, so having a programmer say "I believe this is a tail call" and having the compiler flag them is better than having a system where adding a comma can cause non-trivial changes in the semantics of the code. On the other hand, another part believes that the benefits of using an compiler are that the programmer shouldn't have to worry about such optimizations, and should always get the benefit of them. I think the former is going to win out, because if you're in a situation where you have to have TCO, you have to take care to make sure you write proper tail calls anyway.
I think it's best not to even think of it as an 'optimization', but rather just a different model of computing that the programmer would obviously need to know about. It changes too much behind the scenes to be 'just' an optimization in many people's eyes.
ps. work & school but i'll give you some raw code use cases eventually.