Uhmm... you are ignoring all the Nokia userland stuff. They will have to rewrite every single hildon user-space app/applet in C++/Qt. That includes the file manager, media player, image viewer, pdf reader, rss reader, calculator, clock, sketch, terminal, application manager, backup/restore, connection manager, internet call, chat, contacts, modest, microb, control panel, statusbar and desktop applets, the whole shebang. Additionally, all the "partner" applications will have to be rewritten as well: skype, gizmo, wayfinder etc. I'm guessing the Mozilla (fennec, not microb) people may not be too happy to switch to Qt either.