It's not about whether people have an opinion on Tosin 'making it' it's the idea that someone such as yourself, or anyone, can look at him now & say 'nah he probably won't' .
The point is, it's far too early to have that opinion. He has to improve, yes. I could just say 'nah Diaz won't make it, he wastes too many opportunities'. If he doesn't improve, i'd be right. But how on earth can i assume he won't improve ? And why would i ?
If Tosin was an alcoholic, or dead slow, or thick, shit in the air, or ponced out of challenges, etc, then someone can pick up on that & see a potential future probem. But you can't pick out a kid who plays mostly reserve team football, who has pretty much every footballing attribute going for a cb, & decide he can't improve on a few faults, in the 3 years it will take for him to be the same age as John Stones, who still has loads of faults. if John Stones doesn't improve, he won't 'make it' at City. We are assuming he will.
You can't, Pep Guardiola can't, nobody can, assume Tosin can't solve any weaknesses in his game at barely19.
None of us know. We will only find out, as time moves on. All we know right now, is he has a bucketload of ability. What he, & we make of it, we have to wait & see.