I suppose that like what happened with overlay technique in programming (it disappeared), you could use a bigger FPGA chip with more gates to put all functions you need in it.
But again, it's a waste imho and this could be used, if it will, in small projects (don't want to put the biggest chip in a small drone) or in cheap projects (for instance i can't afford a 100$ demo board, it's to expensive and i'm not craving for it so bad).
Thanks for the Xilinx tip.

For reprogramming FPGA whilst running you need to read the FPGA data sheet.

Some of the Xilinx FPGA allow the device to be reconfigured by the FPGA logic whilst the device is running.