AMD revealed at its Fusion Developer Summit that Trinity's successor, Kaveri, will have true unified memory between the CPU and the GPU. Further details about Kaveri can be read at VR Zone.
After the show, a source confirmed that Kaveri will be a true Southern Islands GCN part in the GPU department, without any remnants of the HD6XXX VLIW-4 architecture, and that the Steamroller CPU core parts there would solve a couple of remaining major drawbacks of the Piledriver architecture.
Whether it includes - finally - each core getting its own FPU and instruction scheduler, or something else like common L3 cache for CPU and GPU, non existent till now, was not answered. The point is, Intel's Haswell desktop with supposedly vastly improved graphics (GT3, 40EUs and 64MB cache) - but likely no such high level enhancement like true shared memory - will be out at the same time. So, getting out Kaveri as early as possible should be an imperative for the AMD APU time.