we can’t really do that anymore.

Good. But even so, Iran is not Iraq or Afghanistan and it won’t be fighting alone.

Afghanistan (103rd GDP PPP) is a really poor country even compared to Iran (19th) with no industry whatsoever and a mostly conservative and illiterate(37.3% literacy rate) population, and yet it eventually won. Iranians are highly educated (85.5%) and mostly urbanized, and those two things can be advantageous. Just look at the ingenuity of the Palestinian(95.0%) resistance, and their locally produced weapons. Urban warfare is hell for conventional armies, the US knows it well in Mogadishu. Iran isn’t blockaded and has allies in Russia and China, as well as Yemen which controls Bab el Mandeb, and Iraq where allied militias keep its vulnerable west secured. Iran itself controls the Hormuz Strait so the US’s is locked from getting supplies into Iran.