The fact that all their parents knew that there was going to still be practice and not even one of the varsity players showed up tells me that these aren’t whiny kids not wanting to run laps but that there are some legitimate problems that the parents see as well!
That being said, these kids will have to face the results of their actions. It may be the coach resigns or it may be that they are off the team the rest of the year, or even next year if for some reason the coach doesn’t leave. They may be rejected from college teams (I doubt any of them are D-1 quality, but even small schools may be hesitant to add them to their roster) And any number of other consequences, good or bad.
It seems similar to a union situation, they are uniting and saying they want something to be different. With a union, if you go on strike, you may get what you want or you may get fired or you may drive your company into bankruptcy.
It will be a learning experience for these kids, for better or worse!