However, some algorithms like Timetravel8, Timetravel10, X11Evo, X16R, X16S, they change the algorithm every block. An FPGA can rapidly reconfigure itself to optimize itself each block; an ASIC cannot. Therefore these algorithms are truly ASIC-proof, in that no ASIC can beat an FPGA (ever) on those coins, unless the ASIC itself is just designed as an FPGA which would be a waste of money since you can just buy ready-made FPGA's.
Correct me if im wrong but i think that algos like X16R still can be attacked with ASICs, you dont have to implement all of the algos that this algo is cycling through you just have to pick the once that are for example 3-4 times even more faster on ASIC compared to a GPU with a much less electricity consumed then you mine when blocks with the implemented algos are coming.