I don't miss sidescrollers, because I play them all the time. Look no further than the downloadable service on your system of choice. Heck, there's nothing wrong with checking out various re-releases of classic sidescrollers either, whether it's through a downloadable service, or a collection like Sonic's Ultimate Genesis Collection. There's also the occasional new sidescroller released in physical form like Contra 4 for the ds(which I played and beat on normal, completed all the challenges, and loved every minute of). That is not exactly what I'd call a current example, but there's also Sonic Generations if you're in the mood for something current(I haven't picked it up, but I hear it's good).
I too hate the notion of a genre dying out if it's one I really enjoy, but I've found that that's not often the case. The jrpg is still around and even point and clicks have found their niche this gen. The only genre I think might have died out is survival horror, which seems to have been replaced with generic zombie slaying bloodfests that are more like survival action games mistakenly labeled as survival horror. Let's hope Silent Hill: Downpour ends up being a proper survival horror title. I hear Alan Wake is decent, but unfortunately, I don't have a 360, nor do I plan on getting one, and that was released a few years ago.