Yes. For every initial shuffle you try, there will be a ~50% chance, that it is more biased to the house than expected. So it's an extremely practical attack, in that sense. And you could also precompute a bunch of "bad shuffles" which you potentially serve to high-rollers. It's 100% transparent, so that's what makes it insidious.  The thing is that it's a weakness of provably fair systems that use this method, so they should simply be fixed.


But the impact however, is pretty minor I suspect. I'm guessing that BJ is going to be the most vulnerable game (because it draws so few cards), and I'd honestly be shocked if you can find an initial shuffle that gives the house more than an extra ~0.1% edge.  (Although I might be wrong, I'm just pulling a number from my ass)