NY is **already** at a major inherent disadvantage, being one of the highest tax states. Which you know. And like every other employer in NY, I'm sure SJU already grosses up compensation to employees they want to attract from lower-tax states to make up for the difference. It's standard practice and it would continue under your fantasy scenario.
If you think taxpayers in all 49 states other than NY are going to sit back and allow a group of highly paid athletes to avoid paying income tax, you're dreaming.