I do not know if the St. John's mercenary approach will work but the best comparison for this is Kansas. Bill Self is a good coach, but it is not going well by their standards given how much money has been deployed and the talent at their disposal.
It's undeniable you need talent to win, but you also need continuity. In a normal Big East, that St. John's team is a 3rd or 4th place finisher so I do feel they got a bit lucky.
Next year's team will be more talented but less roster continuity and more top line guys that aren't used to being 2nd, 3rd, 4th, and 5th options. There's only one basketball.
There roster construction is also kinda weird especially for a Pitino team, like he overcorrected from last year, but we will see.
Suffice to say I think they will be good, but not as good as they should be.