Side scrolling is dead, sadly.
Mario, Sonic, Castlevania, all used to be awesome side-scrolling games, but I guess it wasn't shiny enough for the ADHD aspergers ridden children of today.
Mario's sidescrolling days are still going stroll with his new 4 player co-op/versus game comming up, it's not the first time Castlevania pushes its luck with a 3D version, but different from the others I think that this one will actually be half decent. I'm sure that we will see sidescrolling sequels in the future, they're has been quite a lot of them for the handheld consoles.