The reason they MUST do something about FPGAs is that they are just about starting to be looked at seriously for the mainstream(ish) data enter market, where the new trend is to add as much smarts as possible to the NIC in order to offload as much as possible from high speed networking (100G and up), as these speeds put a significant load on the CPU, and I am not only talking about network stack level stuff but also potentially layer 7 processing. Here having a real FPGA inside the cpu would be a godsend.
You must remember that while the desktop segment (and gamers in particular) are very vocal, they represent a vanishingly small part of the company revenue, that is dominated by server chips (this is also true for intel and nvidia, not just AMD). So anything that gives you market share there is good
Also more and more compute heavy applications are moved to GPUs, making CPUs less and less relevant by the day, and in that segment nVidia has a chokehold on the market with CUDA, there is many times the CUDA software with respect to openCL, so to gain market share there AMD would need a GPU with drastically higher performance with respect to nvidia, also keeping in mind that the openCL software ecosystem (third party tooling, libraries, etc) is nearly non existent.
Oppose this to FPGAs where Xilinx is actually the market leader both in term of market share, and especially in term of technology, on the high level synthesis, software on FPGA, field.