We have been developing and selling FPGA based QAM modulators for DOCSIS and video for last 2 decades but currently all major companies are slowly moving from specialized hardware to software solutions with bare minimum of custom hardware. But some devices still retain FPGAs. All legacy devices sold in tens of thousands also may require support from FPGA expert. Multiple solutions use specialized Broadcom chips that are half way between ASIC and FPGA.

FPGAs are expensive by themselves, expensive to implement in your solution, very hot, relatively slow and require rare expertise from developers. But they have one feature that beats everything - they can be patched in production.