Being the regional hegemon of the Persian Gulf, and let's just accept that premise for the sake of the argument, doesn't make you a Great Power, no more than the Houthis are a Great Power because they can shut down the Bab-el-Mandeb for a while. And this is hardly a game changer anyway, as Iran already had de facto control over Hormuz.

The US position in the Gulf has been compromised, for sure, but it's an exaggeration to say it has been destroyed. And the conflict isn't entirely over yet, so we'll have to see what the final political settlement looks like, if there's a formal one at all.

Comparing this to Vietnam or Iraq is hyperbole, unless there's further severe escalation. At least in the case of Vietnam, there was a major change in the regional balance of power and the US actually left Southeast Asia. Here it's not fully clear yet where the chips will fall. One could easily argue that the balance of power has just as easily shifted in Israel's favor, given the near-total lack of constraint on their exercise of military power in the region, not to mention the ongoing conquests.