I don't think the OP understands the strategy that either company is proposing... both Microsoft and Sony are doing exactly the same thing. They will simply adopt a universally accepted 'tick-tock' cycle of hardware releases - Xbox One (tick), Xbox One 1.5 (tock, Scorpio) then Xbox 'Two' (tick). Sony - PS4 (tick), PS4.5 (tock, Pro) then PS5 (tick). The only exception you might see is simultaneous releases of 'standard' and 'pro' editions with different price tags and capabilities.
Both companies will have new major and incremental releases going forward. The only difference (compared to previous generations) is that both platforms will support forward/backward compatibility. This is good and it mirrors what the rest of the industry is doing. Think of it as apps/services you use on an iPhone 6/Galaxy 6 work perfectly fine on the iPhone 7/Galaxy 7 respectfully.
The games console market is one of the few markets that has required that each 'generation', people have to go out, scrap all their old gear and purchase brand new equipment. Those days are gone (thank goodness). So, in that respect, both MS and Sony are adopting a 'generationless market'.
Yes, it means we will no longer see massive leaps and bounds in terms of technical ability, but it also means we don't have to suffer 10 year generation cycles where the platforms become stagnant and boring.









