@Paul M. Kaplowitz , I'm sad to hear that news. This is a super big challenge, but take some heart from Brian's story and others. My bet is on you.
I can't tell you exactly how to accommodate and/or overcome this new hurdle in your life. I don't turn what you turn. I don't turn the way that you turn. And I certainly am not dealing with the same physical challenges.
I do suggest you look at using an articulated arm hollowing rig to assist in tool holding. Specifically, I suggest looking at either the Harrison Simple Hollowing System or the Elbo2. These devices when coupled with a stand off arm can give you access to both the inside and the outside of a work piece. In my opinion, a long boring bar rig won't be as useful, particularly on the outside, but I have not tried one. Several years ago I acquired the Harrison SHS unit and very quickly began to use it all the time, not just hollowing. You will not be able to use bowl gouges with an articulated arm set up as the tools will need to be held flat (zero pitch), and with fixed roll, but ordinary scrapers, NRS, carbide scrapers, and many of the Hunter type carbide cutters work well, too. These tools can probably shape any curve you imagine. Certainly enough to satisfy.
An head stock that rotates/swivels will also add a lot of maneuverability to compensate for your challenges, but a new lathe may not be realistic right now. Although I notice the lathe in your avatar appears to be a short bed, so maybe not long enough to mount a hollowing rig?
But those are the easy problems. The harder ones to do with one arm are going to be things like threading a chuck on the spindle with your left hand ( a rotating HS would help), and threading/tightening those darn Allen set screws that are everywhere in wood turning. Then there's things like mounting a blank in a chuck or even bringing up a tail stock when turning between centers.
I am guessing you will have to reconsider what you turn, at least initially, and certainly the tools you use. My suggestion is to spend a little time making a list of some of the major and minor operations that you will need to be able to do to turn--it doesn't have to be the full list, but enough to make the point. Then talk to your neurologist and see if he or she thinks a consultation with a Physical Medicine and Rehab physician or an Occupational Therapist might be helpful.
And of course people here might be able to come up with solutions to specific problems.
