At this stage I would say it is hard to say which sportsbooks will stay in the US market for good, because things are changing on a day by day basis. It is worth noting when looking into sportsbooks staying in the US for those who have gone out of their way to de-associate themselves when it comes to marketing within mainland US. As crazy as this seems it actually shows that they are less likely to have any major surprises coming around the corner.
My pick of sportsbooks to stay in the US for the next six months or more are:
Bodog (recently moved ops away from Costa Rica to Antigua and the government there has no plans to work alongside the US, however they have been super high profile that will catch up with them)
BetUS (they have made it so far, and seem to be building a strong brand)
Sportsbook.com (went private, still got the plc thing to worry about, but looks like they are here to stay)
Intertops (they have never been public and have been around for ever, not shaken by recent events)
Some smaller books or those that use their own software and do not rely on many third parties (empire, bookmaker for one).
Just my two cents, and remember at present there are no guarantees and worth just looking 3-6 months ahead rather than a year.
Note when looking into any sportsbooks history you will find some small issues and do not let this bother you (seems to be the nature of the beast). Do stick away from the ones that stiff players as these tend to be harder to get conversions for.