No. He is 1-3 in USO finals, it's not looking stellar there. Federer had 4 USOs when he was 26. Djokovic will dominate the AO but not the USO.
Sampras had 4 USOs when he was 25.
Federer and Sampras only won one USO after 26.
It's hard to win multiple USOs after 26.
If anybody can do it it's Nole. No doubt that he has the potential to get 6+ AOs and 3+ USOs but it's definitely too early to say anything for certain.
btw, saying that he cannot be hc goat because of the loss to Windray is just ridiculous. everybody has ups and downs, including Federer and Sampras. If he gets to 10 slams he will be the hc goat and that is that.