The worrying part is "x265 is still too slow to be useful in most practical scenarios" and "if your CPU usage target for x264 is anything faster than veryslow, you basically want to keep using x264, since at that same CPU usage target, x265 will give worse quality for the same bitrate than x264."

That can mean that there's a real danger that we'll get a lot of worse content in the future, as those who encode may go to use a bigger-number codec because it's assumed to be better (hey, it's newer!) Most of people never encode with different codecs every material just to compare the actual quality.