I lost a finger a few years ago (caught my wedding ring on a nail then jumped down some steps). Luckily I was wearing the ring on my right hand (don't ask), and so it was probably the most convenient one to lose. I still touch-type and finger-pick ok. In fact it was really weird the way my little finger automatically incorporated the role of the ring-finger without me actually having to think about it much at all. Which leads me to think that the pattern of actions is learnt rather than the pattern of off finger movements if you see what I mean.
Good thing it was my right hand tho, otherwise I would have had problems with the chords - altho as people have pointed out, nothing seems to be insurmountable...
I always said it was a cheap wedding ring! (now I have a really thick one, that couldn't cut if it tried).