The areas to the south of the caspian are the most densely populated within Iran, but if Azerbaijan was to offer those populations the possibility of a secular and representative government while under Azerbaijani military control (perhaps heavily administered by Iranian Azerbaijanis), it may be possible to sell them on the idea.
The economic benefits of that stable east-west connectivity would be immense.
If Iran got to that point though, the Americans/Israelis would certainly be a factor however, and would be eager to interrupt anything empowering the Turkish countries which would be next on the menu.
I doubt Azerbaijan would support war against Iran. If Iran Collapses. Azerbaijan is perfectly fine in taking South Azerbaijan.
Lets be honest here i dont think USA and Israel would tolerate a country like Azerbaijan taking care of its own interests.
Its all about balkanising and keeping the region in flames.
As much as I would want Russia and Iran to collapse because they are Turkiye's historical enemies. Their collapse can also be dangerous.
Future of Iran is not to collapse but for it to have Turks ruling the country like in the old days.
Russia would be hella dangerous because people said it would be a true battle royale with every federation having nukes lets not forget the various factions for control. We seen how deadly the Russian civil war was after ww1.