You can't be serious.
Their issue wasn't titanium poorly dissipating heat. It was the back glass. Side rails are not meant to cool your chip in the first place, not to mention that titanium is orders of magnitude better heat conductor than glass (which was the problematic part, not titanium.) And "issue" is a strong word. Their Air is thinner than any Pro, doesn't have any vapour chamber and still manages to match base 17 in (sustained) performance.
To add to that, performance gain 15Pro --> 16Pro was actually bigger than with 17Pro --> 18Pro. And if you want to go even further, their vapour chamber on 17Pro is not actually connected to A19Pro chip in any meaningful way. It's predominantly cooling the battery. In turn, as we already saw in practice, sustained performance is not bad but certainly not astonishing, groundbreaking, or anything beyond what are their usual year to year improvements.