Just take the original code and add whatever cloud functionality you need to "modernize it". The Zune software was easily MS's best invention in the past 15-20 years. Why scrap it? Why not build on top of an already solid foundation? They could STILL do this and call it XBM 2.1 or whatever. Sure it would take a while but I'd be willing to wait for an efficient product.
BRING BACK ZUNE (or it's code)!
BRING BACK ZUNE (or it's code)!