Up to now Canon has not even announced receivers for their own speedlites (580/II, 430/II). I really hope they will - and at a reasonable price.
The problem seems to be that Canon currently has problems with the "reasonable price" part. And if the receivers are nearly as expensive as the st-e3-rt controller, people might just upgrade their complete flash because you don't have to screw a receiver under each older one.
What I'm hoping for is a receiver for dumb ttl and studio flashes that would make 3rd party systems obsolete - pretty please, Canon? We might even forgive you the fact that radio remote still doesn't work with 2nd curtain...
In reality I am afraid, Canon will move very slowly and half-heartedly on this ... until Nikon brings out a way better system.
I'm sad to say that I don't think Canon will update the firmware of older bodies like the 5d2 to work with group flash, because that's the one really important thing that is better on the 5d3. Canon even went out of their way to conceal the fact that hss and radio flash seem to work without drawbacks on the 5d2 :-o