I've only been dx'd for 5.5 years, so I'll give you my mom's experience.

Mom was dx'd originally in 1971 when she had ON a couple months after my birth. She had almost nothing in the way of symptoms for 20 years. In 1990 she started having some numbness in her fingers. She progressed, trying both Avonex and Novantrone, and by 2007 she is in a wheelchair fulltime and at most has decent use of her left hand. She needs assistance with many of her ADLs. She can bear no weight, but she still has a good life, despite all the crap she's been dealt She's an inspiration to me.