Bitstream dynamic rebuilding
Brings back a memory of a company that made Logic Analyzers some 20+ years ago. They used a fairly simple FPGA (or cpld) back then but still managed to put complex triggering algorithms by calculating a new bitstream on the fly and uploading the new variant into the FPGA each time a trigger setting was changed. This also had better timing compared with putting registers in the FPGA and setting bits in those registers to change triggering.
I’m not sure what exactly happened, but I think they had to cancel the whole product line after that particular FPGA went out of production. Using another FPGA with closed bitstream format would have forced them to use the “regiser” way, and would have made the product too expensive, or the timing to slow. They may have switched to a simpler triggering scheme for the “next version” of their Logic Analyzer.