Well, depends. If someone comes into the game with a chip that can basically reduce the energycost and increase the speeds majorly they would have a bigger chance of finding the blocks and thus with enough funding they could potentially reach 51%.
Look at the mining pools of the world, currently China are ruling this space and we don't know how close the pools are to each other.
Maybe you should consider the amount/cost for research and manufacture ASIC chip. Besides it's not easy to make new ASIC chip which is more advance than one created by big companies such as Bitmain and other popular manufacture such as Samsung in future.
Also, i doubt those pool would work together to do 51% Attack and reverse blocks as long as their goal is profit, since continuous attack could make people panic or fooled by FUD which leads to Bitcoin price crash.