Well, at first gamers said dual-core chips are useless. Then that quad-core chips are useless. Now they're testing waters with octa-core chips.
Game developers have always made a good use of the available resources. They'll use the extra power available. The newest techniques they have, like work stealing queues, can scale to a large number of cores.
So games and gamers will use the extra cores. It's much less of a jump from 4 cores to 16 than from 1 to 2.
In (recent) games made with Unity, a lot of workloads like scheduling the GPU and such are offloaded to separate threads with (almost) no developer intervention. Future games will extensively utilize the job system which provides safe and efficient multithreading. Not sure how Unreal and the remaining leading engines stand, but things seem to be looking very good for high core count CPU owners.
Game developers have always made a good use of the available resources. They'll use the extra power available. The newest techniques they have, like work stealing queues, can scale to a large number of cores.
So games and gamers will use the extra cores. It's much less of a jump from 4 cores to 16 than from 1 to 2.
Give it a year or two.