I don't think Kaijufan was proposing adding a New Year's Day special like for Tennant; instead, he/she was suggesting that maybe the two episodes we knew about (the Anniversary Special that's shot/shooting already, and the Christmas special they'll be filming in September) might be themselves a two-parter.
The problem then is you're asking people to pay money to go to the cinema to get half a story.
And? People go to the cinema for a mere part of a story all the freakin' time. ("Lord of the Rings", "Harry Potter" and "Twilight" being the most obvious examples off the top of my head).
But as Captaindemotion pointed out, this is going to air on television, more or less for free. That fact, along with the short running time (compared to most other theatrical releases) make it very unlikely that any rumored "theatrical" release of the anniversary special will ever actually occur, at least as a "stand-alone" feature. However it's possible that TPTB have plans for a much larger Dr Who theatrical event of some kind, which includes a big screen showing of the special, but only as a part of a much larger event.