Symbian OS: A Means to an end
it's fairly accurate to surmise that Nokia always saw Symbian OS as a means to an end, since they've never really promoted the OS as such - you always have to dig into the specs to find out whether it's on any particular phone.
That's really what crippled Symbian OS: Nokia took the amazingly capable and power efficient Psion EPOC32 O/S and neutered it to make it like a Series 40 phone, kludging on a UI which the O/S never really recovered from, to build the Nokia brand, not the Symbian brand.
Which means in turn the genius of Symbian OS - object-oriented from the bootstrap up is just gonna be trashed to make way for traditional kernels along with all the other clever OO O/Ss from the past few decades. Nokia are sailing their Titanic, but the officers jumped ship before it was launched.