Iran would be another Iraq for the US. So regardless of what the 20 year outcome of the hypothetical Iran-US war was, the current political party in charge of Iran would be dead and the installed US puppet government would be considered illegitimate by all the other political sects.
Russia and China would win on their home turf, and get absolutely destroyed in all possible ways if they tried to invade the US in this ridiculous Tom Clancy scenario the OP has concocted.
Iran would be another Iraq for the US. So regardless of what the 20 year outcome of the hypothetical Iran-US war was, the current political party in charge of Iran would be dead and the installed US puppet government would be considered illegitimate by all the other political sects.
Russia and China would win on their home turf, and get absolutely destroyed in all possible ways if they tried to invade the US in this ridiculous Tom Clancy scenario the OP has concocted.