Mari, if you haven't had an MRI you might want one. Spinal stenosis can be central canal or foraminal. Arthritic changes refer to the joints at the sides of the vertebra. But your symptoms indicate central canal. An MRI would sort that and give you a better indication of the likelyhood of any future surgical intervention.
Physical therapy is great, but won't answer your question.
I would guess that you won't need future surgery. But my guess isn't good enough.