Let's take this one by one.
> So no more US military bases in Europe then?
Fine. If the US wants to lose that, it's collateral to the US's political changes. It should have been obvious that this was a consequence, and one bad for the USA - e.g. it's much harder to fly aircraft from USA to middle east without refuelling bases in Europe.
> No more trade with a market of 500 million people?
The EU is always willing to trade, and negotiate durable terms. The impediments to that are on the US side. "no more trade" is an exaggeration of course, but the US's actions will limit trade.
> No more cooperation on science and research?
How much science and research is going to happen in the US in the near future? I'm told that it's not a growth area. The EU and others are going to have to step up here, take in researchers, develop vaccines etc.
> Nothing of the current US isolationism makes any goddamn longterm sense for the US.
Agreed, no notes.
> Europe and the rest of the world will be fine, mostly.
The current petrochemical price shock seems like it will be not fine for Europe and the rest of the world. And they will know who to blame. The silver lining is that it helps make the case for solar and renewables, and accelerate the transition away from fossil fuels.