Disney dumped Narnia because they didn't get as good of a deal with Prince Caspian as they did with The Lion, The Witch, and The Wardrobe and Prince Caspian ended up doing much worse. Disney knew that there would be a downward trend (as the books have) and decided it would not be in their best interest to continue with the series. They still hold the rights to the first two movies, hence why the Prince Caspian attraction is still there.
Disney still could put a Narnia attraction in the parks, just like they put an American Idol attraction in the parks, which is also owned by Fox. There's really no telling what Disney will or won't do. That said, I don't see Narnia having any more presence than it currently does in the parks. I don't think Disney hates Narnia, but they have plenty of their own and newer ideas to go in, Tron being one of them.
Is Tron as powerful as Narnia? I don't think so. Otherwise, Tron would have outgrossed the first one. No matter what, The Lion, The Witch, and The Wardrobe will always be a classic (and successful blockbuster) film. Tron can be recognized as a hit, but I don't think it'll ever reach blockbuster level like the first Narnia or the Pirates series has.
Don't get me wrong, Tron's a great series, but the money in terms of box office gross just isn't at those levels. I do think we'll see a Tron attraction before we'll ever see a Narnia ride. The reason is that it'll be far more easier to do Tron and unlike Narnia, Disney is on board for more films which will keep the attraction popular.
If Disney did it right, they could make a timeless Narnia attraction just like The Haunted Mansion or Tower of Terror are considered timeless. I don't think it's a investment worth risking since Disney has little to no stake in the future releases. If anything, they might participate with Fox in a boxset or something, but nothing more.