What are people really arguing here? The ps5 will have a 60fps mode, at least the pro. The real question is, at what cost?
We can kinda estimate it, actually.
We know how gta5 looks in 60fps mode on ps5.
Now lets see how last of us remastered on ps4 looked in 1080p60(mostly stable altho not perfect, some dips in heavy scenarios) fps:
vs how proper 1080p30 looks, made from the ground up:
TLDR: gta6 30fps if its gonna be priority gonna have similar jump to what tlou remaster on ps4 vs tlou2 had, so generational upgrade, we saw all that in first and 2nd trailer,
If they make 60fps as a priority and 30fps mode will just be higher res/less pop in, then ofc it will not be as impressive(talking gameplay here, we know cutsceness can look amazing in ds2 for example yet compared to gameplay models its at least full generation apart).
Personally i would love for gta6 at launch(so consoles) be as low resolution as possible and have 30fps only, we know game gonna come out on pc, on next gen consoles and likely even on next next gen aka ps7 in 2036 as a remaster/definitive version so plenty opportunities to experience it in full stable 60, but whats important is to have that super high graphical fidelity base on the consoles so we can scale up from that, in similar way we had ps360 version of gta5 that also was too demanding for those consoles when it launched, then next gen versions/pc versions had at least room for improvement both image quality and fps wise on top of other settings.