Some examples of races where Massa was faster?
Germany, Turkey, Brazil
This trend, of Massa catching up to Michael, would have continued into 2007 and 2008, with Massa getting better better, and Michael only getting older and going off his prime, no doubt about that.
And so a proof is MS comeback with Mercedes, he was only a shadow of his former self.
However, thinking more in-depth of the full scenario, we would have:
-Kimi doesn't join ferrari so he stays at McLaren.
-Alonso doesn't join McLaren so he stays at Renault.
Alonso not bringing 6 tenths to McLaren so then Ferrari was dominant again? 
Very hard to predict with this whole different scenario indeed.
Kimi vs Hamilton at McLaren, who would have won? Hamilton probably but thanks to the switch to Bridgestones, which would've made Kimi start from scratch and adapt, even if in the same team.
Most likely a battle Hamilton vs Schumacher for the championship, with Kimi and Massa there or thereabouts, kinda close.
Alonso somewhere right behind the top 4, the Renaults would drop (and did drop) in performance with Bridgestones.
In any case, as I said, a 38 years old declining Michael may have still won, but still not dominating, pretty sure, he would've needed to work very hard against the young guns.
Edited by RacingFan10, 28 October 2023 - 10:33.