'So you actually believe that in the (very unlikely) event that Trump becomes President, US will lead an isolationist policy and shut down its sphere of influence around the world? '
Yes, if they don't stop Trump, then that is what will happen because Trump is in the tradition of the legendary real conservative, Pat Buchanan, where an America First polcy will be pursued not an internationalist UN global warming policy. America will retrench,impose trade tariiffs and follow a "fair trade, no free trade" polcy as Trump says. America will stipulate the rules and everyone will follow and America will do deals under Trump with Putin and China etc and everyone will know exactly where they stand. There will be no more underhand support for regime change and all teh rest of it, no toppling of secular regimes fighting Islamic fundamentalism but deals will be made with them instead and they wil follow America's rules and the whole world will benefit from the stability and the growth and prsoperity that will follow. Deals will be made to create a new financial system that will keep America rich but will also share the wealth across the planet.
'What - close military bases in various countries, call back its soldiers in Afghanistan, Iraq, etc and let these areas fall into Russia's hands? '
No, the zero sum game of constant conflict will end as international deals are done to promote trade and business and investment and coal fired power plants for India etc so that humanity prospers rather than exploiting of regions for the profit of the 1%
'Will US be quitting NATO, then? Such a clever bunny like you must surely be aware that much of US's military commitments are there because of NATO deployment. '
No, but the military expenditure will be able to be scaled down as Trump gets on with Putin so that Trump and Putin can divert money from the military industrial complex back to creating jobs and infrastructure for the people.
'"He says he will get on with Putin"
Oh yes, isn't that totally believable. Don't make me laugh.'
I think it is believable. I don't believe that Putin is a psycopath and like Hitler as the corporate media tells us just as I didn't believe that about Gaddafi who created one of teh richest countries in Africa with good education and health and which has now been destroyed and handed over to Islamists after Sarkozy and the career politicians destroyed it.