If the US government forces American ISP’s to ban online casino sites, assuming that is even possible, can’t you just get around that by using a proxy located out of the country?
I think the worst that can happen is ISP’s being forced to report your Internet usage (like downloaders), and if it involves online casino transactions you get busted. I don’t know if this is possible either, but I think I read somewhere ISP’s record your Internet activity for 3-months or so, so possibly such data could be incriminating.