SCTP is a good start for sure, and someday may make sense. The problem is a deployment one: it can't pass through NAT, making it off limits to most users today

SCTP is a good start for sure, and someday may make sense. The problem is a deployment one: it can't pass through NAT, making it off limits to most users today. As for solving problems from the transport, that is not true. I assume you're suggesting that streams can only be tackled at the transport layer, but SPDY's compression is clearly an app-level endeavor.