This is only rumours at the moment anyway, and I'm not sure it'd ever happen. Similar to Wizard of Oz (touching on what Bastian would ideally like to happen), Mary Poppins is a film classic, so doing another version and not being overshadowed by its predecessor would be a tall order. I doubt there'd be many takers. Very few 'classics' get the remake treatment (I'm thinking of Gus Van Sant's Psycho remake in the late 90s, which is all but forgotten now).