I have some TBM friends I visit in Utah every few months, they still slip and say mormon in conversation, and then correct themselves in akward backflips of verbal circumlocution. I think most will just slip back to normal speech within a few months.
Nelson will quickly be forgotten once he passes on. The focus will be on the next guy. Mormon will still be used to refer to the church and it's members. The only way to get rid of it would be to do what the RLDS did. Rename the church to a shorter Christ focused name and put everything from Joseph Smith on the back burner.