I think if there was a movie, RTD would be the absolute perfect person to write it. The stolen earth/journeys end had the scale, emotions and grandeur more so than many of the biggest blockbusters out there today, and judging that all his finales were of good quality, as were the majority of his episodes, I think he more than proved he knows how to write who.
If they did consider a movie though, I would like it to be done in the way of the 50th, wherein, it's the current doctor (with one or two returnee doctors as well) and it dosen't contradict anything said in the show. With RTD at the helm though, the man who loves who and creator of new who, I doubt there would be any problem, as i'm sure he'd absolutely wan't to keep it in line with the show.