This has been bugging me for ages and that is the current state of the Enclave after their defeat in the Capitol Wasteland. For a while I could barely find anything in F4 except a few mentions that were few and far between that gave no real evidence of their current state, but with the release of Far Harbour there is some new information and that is from ex-Lietentant now Children of Atom Zealot Brian Richter. when passing an easy speech check about army he was in and he replies. "They called themselves the Enclave. They were a force to be reckoned with in their day, but now... well, it's been a long time since then." Now this suggests some things....things that make me worry like is the Enclave actually gone? maybe but can we trust the word of someone who has been out of touch with the Enclave for what I can guess is ten years, I'm gonna say no atleast to the destroyed part I believe him when he says they used to be power but I believe that if the Enclave can survive the destruction of the Oil Rig they can survive the events of Fallout 3 and there is evidence supporting this.
First. The Enclave didn't just have bases in the CW they have outposts in Chicago and theres likely many more bunkers they can occupy across the United States.
Second. After you destroyed the mobile base crawler you can see multiple Vertibirds leaving the CW as you wander around. (I Remember seeing three leaving at Takoma Industrial.)
So with this I firmly believe the Enclave is not destroyed just in hiding and regaining it's strength.