What you are describing is called an 'overlay'. Basically an overlay is some sort of computing architecture built with/on top of FPGA fabric. Soft processors ar

What you are describing is called an 'overlay'. Basically an overlay is some sort of computing architecture built with/on top of FPGA fabric. Soft processors are an example of overlay. You could imagine some kind of special linear algebra computing engine, etc. as other examples. RISC-V soft processors already exist. I'm pretty sure you could find some open source projects floating around. The trick is to make something that could actually out perform existing FPGA/CPU devices (SoC). Xilinx, now AMD, makes quite affordable Zynq Ultrascale devices that have FPGA+ARM-CPUs+GPU in a single device. The idea here is to use existing ARM architecture, but accelerate important functions. Developing a complex overlay would be quite a complicated project, so for many applications, it is only necessary to customize specific functions. But either way, best not delay, because who knows what AMD will do in the future, and like you mentioned, Intel(Altera) already abandoned everything except big data-center stuff..