You have asked a billion dollar question, brad 
I think this will take some time, won’t be as soon as you expect, but the industry has to be regulated some day. Like Dom has mentioned, the online companies have to be 100% clean to enable the land based gaming companies acquire them. This is a logical step for regulation considering the fact that the land based companies have enough clout in US to get the regulation passed.
There is a need in the market to gamble and currently players play at casinos which accept US bets. Considering the market economics, government can’t enforce a a ban completely because there would be always some operators which will accept bets. Therefore in the interests of the players and the tax coffers, it makes sense for any government to regulate and have some level of control on the industry.