You quite literally need a tablet to achieve absolute positioning. It might as well be the minimalist sensor setup to achieve accurate triangulation data. Your absolute positioning will never extend outside of the area of your "tablet" device. With that said, if you were to use a mouse with a "tablet" device you could achieve absolute positioning but then you are basically just use a giant mouse shaped pen and you've defeated the entire purpose.
If the question is, will I ever be able to use a mouse shaped pen with a tablet? Then the answer is most certainly. But you'll never be able to use just a mouse for absolute positioning. The best you can hope for is that huge leaps are made when it comes to reducing the error on each sensor calculation such that drift becomes negligable. Even then, it will still exist since sensors will never be perfect.