This is a very good, very pragmatic idea.
The latency issue with the protocol is just immense and this takes a whack at a main issue, but doesn't quite get to where it should. One of the main drawbacks is you still have to wait for the first reply before you can request any associated content, which is bigger deal than it seems. The second drawback is it requires the website owner to do this by hand and invariably they'll bundle things in the wrong way, not account for differing network bandwidth types or simply not do it.
That said, for some very good reasons, this is good direction, so we'll see what happens.