But this was likely locked up years ago before this boom. Will Apple still be the premier customer for TSMC's next node A14?

Apple was actually told by TSMC to move off of N3 asap because Nvidia with its Vera Rubin and Google TPUs will take over.

Semianalysis had a great and detailed article about TSMC & Apple and how the future might play out: https://newsletter.semianalysis.com/p/apple-tsmc-the-partner...