Eau Rouge is flat nowadays – there is no “traction” to speak of out of Eau Rouge; the cars are not limited by traction but rather by power on the exit of eau rouge.
About La Source, Vettel went through a compromised line through La Source as he had to defend his entry; as such his exit traction was compromised a lot; re-watch the start and you’ll see what I mean.
I think there’s a slight misunderstanding of terminology here – the tyres go “off the cliff” BECAUSE they are destroyed. They’re not two separate incidents.
I’m saying I don’t think Vettel would have pitted on his own accord in those last few laps. If he had been overtaken by both Jenson and Fernando then he would’ve pitted; as it was the safer option. But had that not happened, I don’t think he would have sacrificed the slight chance of victory provided by not pitting. For example; if you were in that Red Bull and had Fernando and Jenson behind you; and you’ve held them back for 20 laps. You’ve been on your tyres for 50 laps; but it’s Monaco. There might just be a chance you could just keep driving as wide a car as you can and they wouldn’t be able to overtake you. If they finally did overtake you then; fair enough. Let’s pit; get some fresh rubber, and just bring the car home (as I remember it he would’ve kept 3rd even if he pitted). Otherwise there’s a slim chance of victory.
He might have won it; he might not. Who knows? On lap 70 or whatever it was the SC came out, Vettel was lapping so consistently that he was doing the same lap time (give or take a tenth) he was doing on lap 17 (his first flying lap out of the pits).