Steamroller will not be some huge great thing that tramples on the Piledrivers. It's not happening on AM3+ meaning it isn't a balls out performance CPU. It's an 8 core APU, that should have enough grunt to mimic the consoles. It's also an attempt at lower power usage. So basically it's like a low clocked locked haswell I5, versus a 2011 set up.
Well, Steamroller may come to AM3+. It's not a dead socket until AMD says it is. Kaveri is the Steamroller APU for FM2+, but I think it is unlikely to have 8 cores unless AMD releases a CPU-only version. It's possible we may not see any new 8 core CPUs for a while, but it seems to be missing out on a massive area considering the gaming potential with new engines.