That is the best outcome.
Rebif, nor any of the other three firstline meds, are considered cures.
Rebif is an excellent med with a good reputation. And therer are other meds that are coming along soon that will be in pill form, but it remains to be seen who will do best on those versus using the shots.
Now, the reality is that a good proportion of people with MS will need some aid for walking and other activities (like a cane or wheelchair) within about 20 to 25 years after diagnosis.