Since the editor will now load on mobiles too and the Bb Code textarea fallback will no more be automatically loaded, for users with old mobile devices and/or with exotic browsers, it should be better and safer to set an user option to enable or disable the editor on his mobile device. If you find time you could also implement a real Bb Code editor. I do think MarkItUp is the most flexible and easy to do that. If you want to keep 1 line of buttons, you probably won't have to edit the core files. Other solution: the one coded by Luke. The biggest things to do will be to try to use the same css of the rte editor and to integrate the same overlays than the new ones.