Odds of Hanging On
Couldn't be better. Nursing is the fastest-growing industry there is, and job opportunities are bountiful. Mainly because there are so many people on this planet, and modern medicine keeps finding ways to prolong their lives. Whoops, are we repeating ourselves?
What we're trying to say is, hanging on is about as easy as getting in. Hospitals will never say, "Golly, we've got enough nurses and don't have a need for any more." They'll always need a few more hands on deck. Unless you get caught smothering your patients with pillows, you should be set for life.
However, nursing can be a hard career to stay in for decade after decade. Night shifts, being on your feet for hours, and dealing with sick, crabby people all the time can get tiring. If and when you decide to go (whether you're retiring, switching to a different role in the hospital system, or changing careers altogether), it'll be because you want to, and not because you can't find work.