Obviously fans would pick a new Pixar/Disney animated film over a 3-Dization of a prior film. Lion King was one of the biggest animated hits of all time before Pixar, and being the first 3-Dization, it may have had a novelty that wore off.
I wonder how long the lines for Mermaid are at MK?
Given DCA's version of Mermaid, I can't help but feel that the attraction hurts the franchise. Since it only costs a couple million to the 3-D treatment, I bet they do it anyway on Mermaid since the work is partially done, and that they release it on 3D DVD.
If Maleficent is a success, I wonder if they might consider doing a live-action Mermaid film, maybe even change the story a bit (they changed the story for the ride). I think a live action Mermaid film could even be magical and a bit mysterious if they focused on Ursula before/during she became a sea witch. And who wouldn't want to see an Ariel with a human top-half and a CGI Mermaid tail bottom? The Mermaids in Pirates look pretty cool.
Mermaid the ride is sort of . . . late to the game in terms of an attraction, and something needs to be done to reinvigorate the franchise, outside of the adventures of Melody.