While I cannot begin to guess where and how things will shake out with all of the technical stuff and developer support, isn't it safer to assume that 9th gen consoles (PS5, Scarlett) will
not have RT hardware? Aside from all the talk and hype for cloud streaming, and I'm not buying into what Ubisoft said about 1 more generation of traditional consoles. So assuming there is a 10th generation of traditional consoles (i.e. PS6, Xbox Zodiac, or whatever) with all the processing hardware and RAM in your home, around 2026+ (or late 2020s) that might be the soonest consoles would have hardware RT support, and enough time gone by for realtime RT for games to have matured, shaken out and improved in terms of cost, etc. And not counting hypothetical mid-gen upgraded 9th gen consoles (i.e. PS5 Pro, Xbox Scarlet XX).
Of course, even by the late 2020s, realtime rendering will not use 100% raytracing or path trading, but some combination ray+raster hybrid. I would think. Could be wrong, but, then remember GDC 2018's RT for games roadmap: