I think it also depends if they stick to 30fps for rt mode, if they do then with pssr 2.0 potential for some more rt is very real, if they will "upgrade" 30fps rt mode to 60 with rt, we can say any more advanced rt implementation goodbye
For comparision 16gigs rx 9060xt here (which is rough estimate how ps5pr0 performs), 1080p but with fsr on quality, no fake frames, gets full rt including psycho lighting settings(obviously no pt) and game sits at around 50 when there is barely nothing on screen, it will definitely drop much lower when shit hits the fan, so 30fps pr0 mode with those settings would be doable 4sure (pssr 2.0 instead, and native res below 1080p, maybe not 720p but 900p or so? ).
TLDR- with pssr 2.0 aka internal res being relatively low(720-900p) and 30fps mode we definitely can get proper rt on the pr0 finally.