I can't give an exact answer, but I can add a few thoughts that might be helpful. First, the law that will increase taxes to this point hasn't passed yet (though it seems more likely than not right now), so I wouldn't make any immediate decisions before that happens. Second, the schools know this is happening too, and they know a lot of their students can't afford it. In the long run we can expect schools to increase compensation and decrease the number of graduate students they admit to compensate. We're unlucky enough to be caught right at the point in the middle where that hasn't happened yet, but odds are compensation will go up enough to be livable in the next few years.
Bringing it back to your original question, it's possible wages might be extremely low for a year or two while colleges adapt, but will likely increase to at least subsistence after a little while. Unless the application costs are a barrier, I would still consider applying at least to your top programs, maybe forgoing some of the lower level ones that wouldn't be worth the stress of low income. Lastly, I would recommend getting in touch with one of the programs you are considering about these concerns. They are probably worried about it too since they are looking at half or more of their graduate students starving, so they might already have plans they can let you know about.