He could have stayed and continued his education with bielsa. Could have been the next to take over. All he will learn with huddders is how to be miserable.
The thing is, they're only getting Corberan. Even if he was as good as Bielsa (and tbf, he was excellent with the u23s before Bielsa arrived), he doesn't have the entourage that Bielsa has built up over the years. We'll have the same problem when Bielsa leaves, unless he retires, we sign Corberan, & Bielsa 'donates' his team to Corberan. Wildly speculative, but suspect I won't be too far off the mark.
For me the only coach in the world who comes close to Bielsa is Guardiola. Pep has been brilliant at Barca, Bayern & City...but he's never taken over a mid table team and turned them into champions whilst still balancing the books. It's a nice notion that we could somehow repeat the Anfield boot room successes of the 70/80's but it's highly unlikely.