My late AH held a job where he was responsible for quoting jobs worth millions of $$$$, and did it successfully for 30 years. Just 5 short years after he retired, he couldn't even work out his pension, and daughter had to take over.
He went from a drinker who was very capable, to just functional to totally inept, in 6 years. There is no chance that your man will stay as he is, certainly he will not get better, but there is a 100% probability that he will become a parody of the man you love.
Follow the wise words from those who have been in that same place, sometimes a few times.
God bless