For Intel, I guess no clear business case, or something. Integrating FPGA support with operating systems seems like an interesting problem too, and perhaps one which needs some effort before desktop/server systems add this.

In the embedded world they're available and not even super new, the Zynq[1] from Xilinx has been out for a few years. It combines an FPGA fabric with hard ARM CPU core(s).

Intel (through the acquisition of Altera) also has such products, like Stratix[1] which also combines FPGA and ARM. I seem to remember seing some x86+FPGA for embedded applications from Intel, but didn't find it with a quick search.

[1] https://www.xilinx.com/products/silicon-devices/soc/zynq-700... [2] https://www.altera.com/products/soc/portfolio/stratix-10-soc...