I posted about a week ago that we have been into the Riviera within the past month. The Riviera has new owners and SOME money is being put into it. When we were at the Riv, we noticed new lounges, food court is full again and a decent amount of people in the casino. I think they will continue to struggle, but I believe they will survive for awhile longer (at least several years).
Circus, Circus has been paid-off for many, many years and since it is popular with the "we have small children and can't afford the City Center" group, it will be fine. Plus, remember that it is owned my the MGM group, so it has a financial safety net in place.