The US regime is changing with the next presidential election regardless of the outcome (or lack thereof) of this war. Short of a nuclear exchange or China invading Taiwan or San Francisco, nothing is changing that.

The Iran war was one of the biggest economic boons Russia could hope for; the disruption of oil and gas exports from Middle East with the associated spike in global prices brought Russian economy back from the dead, as now their exports are so much more valuable.

They're not though. They're lofting sanctions on Russia just to help try to survive this war.