Depends on if they stay the enforcement of the decision while the case is pending or not. I think the kids saying that the law does them harm would have a strong case for it being put on hold until the case is resolved, meaning they'd be able to sign NIL deals. I'm no lawyer though, so maybe that's a bad guess.
That could be one of those things where it simply comes down to the philosophy of the particular judge the case ends up with.
Of course, we're also talking about Texas....high school football is practically religion down there. If schools across the state start losing their best players, be it to an early college start or a prep school in a more NIL-friendly state, then a court challenge may not be necessary. State legislators will be under so much heat from constituents that they will simply amend the law on their own.