Tbh mate, my feeling is that this is his plan. He wants to come here and do two things:
a) break Rooney's record; &
b) match or surpass Messi's 6 (likely 7 now due to the Copa America win) Ballon d'Ors.
I think he's going to be here for the three seasons at a minimum and if we're going well, I think he's getting another year or two on top of that.
It's difficult and for literally any other person in any other comparative field I'd have said it was impossible, but Ronaldo defies convention. He's still having the same productivity at the very top level as he did when he was at his peak. And looking at videos of his time at Juve this season just gone (which didn't just include his goals, but also his all-round play) his acceleration and speed is still pretty much enough for anyone he came up against. He isn't going to be found physically wanting at all.
The hope for me is that just like Cantona, he becomes the totem around which this young team grows. And if that does happen then honestly, I can't help but tip my hat to the club for it. It's a potential masterstroke and his impact could reverberate for years after he's gone and would solidify his legend status at Utd, perhaps even putting him on that hallowed pantheon which tbh I never thought he would have reached after he left and had his peak years with Madrid.