As is, the US can stand-off and torment Iran for a very, very long time.
$31 trillion economy. $94,000 GDP per capita (nearly 3x Japan for reference). The US can spend $100 billion annually on bombing Iran for the next decade entirely without harming its economy in a meaningful way.
The US doesn't have to let off. Iran is pinned, massively eroded, and the US is only losing money. Iran has lost all of its proxies, its military is entirely broken (and fully capable of waging a guerrilla conflict), its navy is gone, its airforce is gone, its military manufacturing is substantially eroded, and Russia is boiling. The reason the US is going back and forth on peace, is for the same exact same reason it's in the US interest to bleed Russia. It's this: let's pretend we want peace, while we endlessly grind Iran down.