I think this conversation was derailed. I actually wanted to avoid mentioning variadic generics for now, because I believe that's a more complicated discussion. Personally, I would also prefer a revamp for tuples, as a struct with variadic generics, but for now, I am suggesting something simpler.
Why not simply allow extensions/conformances for tuples of fixed arity? I agree with the comment in this old thread that we may run into some complexity risk by encouraging people to make a bunch of conformances at different arities. However, it would still reduce the current boilerplate that is required, where when we want that behavior we simply wrap tuples of fixed arity in struct and make those structs conform to the desired protocols. So, why not go for this solution until variadic generics are supported?
I also believe the two issues are kind of orthogonal, in that support for variadic generics could still be added later and this feature would be unaffected.