I think the only way we'll see any new attractions added to the current World Showcase Pavilions is if they are focused on an IP. For example I can't see the 'Rhine River Cruise' being a major pull if Disney decided to bring that project back from the depths, but Ratatouille or Beauty & the Beast would definitely bring in the crowds.
For me any new ride added to World Showcase is a huge bonus, as much as I have grown to appreciate it now I'm older, when I was a kid (and I'm sure is the case for a lot of children) once you got past the rides in Mexico & Norway, there is/was not a massive amount to keep young ones, who want to ride things entertained, although I appreciate that this has changed with Kidcot and the World Showcase Adventure games, but these weren't around when I was young.
Also, yet another rumour has sprung up regarding the possibility of adding Brazil to the World Showcase (source Blog Mickey
), which is certainly very interesting, and again would be fantastic if true, another country would certainly inject new life into that side of the park.
I can't wait to see what gets announced at D23.