Rumour: Microsoft planning to merge Windows Phone and Windows RT over the next two years

Microsoft insider MSFTnerd has posted an interesting rumour on twitter.
He claims Terry Myerson, newly promoted executive vice president of operating systems, has decided to slowly merge Windows RT and Windows Phone over the next 2 years.
The feat will apparently be managed by 3 regular General Distribution Release updates per year. 
As an early move in that direction, Microsoft is also rumoured to be merging the Windows Phone and Windows 8 store.
The question that remains is if Windows Phone and Windows RT’s UI will also be merged, or if Microsoft will end up having different user interfaces for different screen sizes.
The rumoured move, and Myerson’s promotion itself, is indicative of the increasing importance of mobile – while people have to use laptops and desktops to get work done, they prefer using their phones, which is a dangerous trend for a company like Microsoft who’s dominance is tied to the former.