Good question. I think that:
# Things may well get worse before they get better
# Yes the US will eventually regulate (but it may take years)
# The reputable Casinos would generally credit back old players BUT the process of consolidation that goes on in the meantime may mean many brands have merged/sold/disappeared.
My conclusion: no harm in finding new US players; definately plan a US strategy for the future; time better spent now targetting other countries.