If you're just starting out learning programming, it hardly matters if M$ still supports it; it'll still provide useful experience.
EDIT:
also it should still work fine. it just means that if you run into any problems that have to do with xna itself or later windows updates remove xna compatibility, you'll be on your own (along with anyone else still using it anyways lol) instead of having M$'s own support
EDIT:
also it should still work fine. it just means that if you run into any problems that have to do with xna itself or later windows updates remove xna compatibility, you'll be on your own (along with anyone else still using it anyways lol) instead of having M$'s own support