Okay... interesting times for all concerned. EU (read Germany) may just go ahead with economic ties to Russia & China. Besides, Russia has always historically felt great inclination to be seen as a Western power, not an Asia power.
China will be jumping for joy - turmoil in ME means more people to sell weapons to and cheaper Iran oil.
Afghanistan is going to get fu*ked, seriously Iran is a stabilizing factor there.
pakistan will get a short-term breather.
Indian officials will be pulling there hair out and what will follow is frosty Indo-US relations till the next US president comes along (democrat) - Trump is not going to last.
If Iran gets destabilized, there will be a huge vacuum. Iran has always been there. Since ancient times, it was India stretching upto Kandahar and then Iran stretching all the way to Arabia. Iran is not going anywhere. But a weak Iran may lead to the creation of more separatist movements and perhaps a greater Balochistan.
Our engagement in Afghanistan will fail. Badly.
But, Iran isn't going anywhere. US can't ditch India after all Obama did. We are too important vis-a-vis China and Austraila is becoming less reliable everyday. That leaves only India, Japan, Vietnam, maybe Skorea and Taiwan, & US who want to do something about Chinese.
Wild card is Russia.