It's almost over for lumia and blackberry. So why not unite and deliver a combined ecosystem. Bb10 +Iive tiles+ office 365 + here maps + best of lumia HW and bb HW + amazon store.
I'd sooner want the UX of Blackberry 10 powered by Android. The Priv is kinda close ish but nothing quite there.
Also uniting would be a pretty awkward operation.