There was a definite legal issue between Chris Sawyer and Atari, but I have no idea how that was left and where the RCT name was left.
There IS RCT coming to the 3DS though and "Thrillville" was released to try and build on the popularity.
The games (all three) have actually been massive commercial successes though. While it may only be enthusiasts who "keep the torch burning", the overall sales are very very good. Unfortunately, Atari underestimated their user base and produced Thrillville, which is a dumbed down mini-gameesque load of casual bollocks.
While RCT is a long way from realistic, it's still captivating and does a fine job of making you believe (and some people really do
) that you can build and run your own theme parks. Chris Sawyer knows exactly how to make these strategy games, hence why he was so upset with what Atari did with the franchise with RCT3.
Anyway, there's very little to zero chance of an RCT4 (no matter what the potential commercial success). The world has indeed moved on and I just don't think the series is commercially relevant in it's current form (or in it's new form either). The PC gaming market is a shrinking one, with most "casual" gamers who would have bought into the franchise now on consoles.