Kaveri (which is based on Steamroller) will basically roll out with this feature.
On top of that... AMD stated that they were focusing on fixing single-threaded performance on Steamroller cores and that with all the modifications, 30% to 40% performance gains in CPU performance should be seen.
So effectively speaking, the 1 module that contains 2 cores won't behave like a single core Intel CPU, but instead will behave like 2 cores i series CPU.
Right now (at least in the mobile area), the A10 4600m is comparable to an entry level i5 Ivy Bridge in terms of overall CPU performance.
If Kaveri CPU performance reflects AMD statements, then quad core Kaveri APU's will basically be comparable to Ivy Bridge/Haswell in CPU power alone... and probably surpass Haswell in IGP performance.
Adding to all of this, seeing how consoles like PS4 and Xbox have adopted AMD x86 hardware, it hUMA will probably find itself in widespread adoption... not to mention utilization in multicore cpu's, and adoption of x86 instruction set (it will be far easier to port games from consoles to PC's... they should be far more optimized compared to what's done today).
And of course, graphics will likely experience a very high jump.
All in all, I'm interested to see what Kaveri brings.
I just hope that OEM's decide to build proper mobile platforms for those APU's instead of putting an A10 4600m into a 17" monster.
Current AMD APU's are ideal for 15" and lower form factors... but their adoption is extremely low to the point of non-existance.
Heck, even AMD's mid-range mobile 7xxx series GPU's cannot be found virtually anywhere.