Like he will be at his death bed, at probably at age 90s or 100s, his hand held by Maika both of them watching some current news on their wide screen monitor about a nuclear war about to start all over the world.
Ash would probably ask Maika if all the things they've done - bringing back 'civilization' was all worth it, when along with it they also bring back the 'destruction' that is its by-product. Maika would probably console him, saying that what he did was create a bright future for everyone and the destruction that came along was created by others who dream of their own vision of the future.
But all in all, Ash would probably close his eyes for the last time, knowing that he has won over the greatest tyrant, which is time itself. By this time, he probably already managed to create a system that will store and keep knowledge perpetually so that even if civilization ends itself once again, another 'Ash' in the future can rebuild it all over again.