Same for the ESL.
The ability to kick the golfers out of the majors has teeth. However, there are several other players in that game - the Masters, the USGA and the R&A. A breakaway tour seems unlikely to succeed, but if it does it's possible to imagine three of the majors jumping ship and the PGA Championship being left with diminished status. The PGA always has had the least status of the the four.
If a breakaway tour does get going, it's easier to imagine older names like Mickelson and Rose signing on (as they have less opportunity to add to their major haul) than golfers in their prime like Johnson. That said, if there's enough guaranteed money it may be hard to say no. Golf is a notoriously fickle game with thin margins, and top golfers are generally an injury or a hitch in their swing or putting stroke away from their income cratering.