It's questionable whether QNX has any advantages over a Linux kernel anymore, and BB10's application APIs were unremarkable. I've used Meego, and it's a nice tablet Linux, but it has nothing like the userland innovation of Android, with a unified managed language runtime for both apps and system middleware. Both Android and iOS created new app APIs, and new UI/graphics stacks on top of open source kernels, and new multimedia stacks. They both went much farther than "a nice tablet Linux."
While Nokia had the resources to succeed in smartphones, and a unique market position with S40 that would have been even stronger but for some of Elop's decisions, I don't think one can claim Meego would have been a slam-dunk. None of the efforts to mobile-ize Linux that have been short of the kind of rethink of the userland that went into Android have gone very far. Tizen, Jolla, Meego, and Canonical's mobile products are all variations on the theme of incremental changes to Linux, all with about the same outcomes.
While Nokia had the resources to succeed in smartphones, and a unique market position with S40 that would have been even stronger but for some of Elop's decisions, I don't think one can claim Meego would have been a slam-dunk. None of the efforts to mobile-ize Linux that have been short of the kind of rethink of the userland that went into Android have gone very far. Tizen, Jolla, Meego, and Canonical's mobile products are all variations on the theme of incremental changes to Linux, all with about the same outcomes.