Actually since Bitcoin and legalization in the states, moving money is no problem compared to a few yeara ago.
And the Feds already know everything, they just dont care as much anymore since sports betting isnt consifered taboo any longer.
Lastly, 2 things:
The U.S.market is only a percentage of players for these books. Which means their business will continues as always.
Also, the more states & companies offering legal sports betting in the states, the more competition there will be, just like with offshore.
Meaning, sports sites such as this can make the transition, and still keep rolling along.
There will always be bettors wanting to share & gain info, not only those existing, but even many more as legalization spreads.