Isolationism is a fine policy except it's fundamentally flawed on its face because it doesn't discourage aggressors in general and jihadists in particular, especially al-Qaeda, whose primary mission is the "overthrow of the godless regimes and their replacement with an Islamic regime." We need to drop the ethnocentrism and understand that they don't think like we do. These "people" only respect force and are emboldened by/exploit weakness. It's not a coincidence that attacks by al-Qaeda affiliates have tripled since 2010.
The lesson we should learn from the last 25 years is not isolationism... it's (do you really want to hear it?)
As I said, I don't think you can go into isolationism after you've opted to go in and mess with things. Unfortunately, we've been messing with things for so long, and it's not working, that we can't exactly just pull back everything overnight and yell "Best of luck with everything!" as we softly close the door.
It is possible to, though it would never be acceptable with the public, to provide a show a force and still remain isolationist. We would just have to over-respond every time someone poked at us. Radical Islam would eventually realize that we are not to be messed with when the slightest provocation ended up with a massive retaliation.
But this is all moot - we're way past this point now, and there is no good solution.