Of course he can. People said Rafa would never win another slam. Look how that turned out. Okay, Nole may not be quite so talented as Nadal (or completely dominant on one surface) but it shows that counting people out like that is senseless.
With his talent, he could win a few more, certainly.
Don't sleep on Nole, peoples!
Yeah, sure compared to Rafa and Roger and a few other greats, they'd won multiple slams by Novak age, but that isn't the norm. I haven't lost faith in his talent.