He might had liked very much the experience of writting a musical and maybe has considered that touring needs too much time nowadays, time that he could spend with other different things he didn't try yet...
In the other hand, there is no need of retire of playing live. Eric Clapton is retired of touring in the terms MK tours, but he still play around ten concerts per year between the RAH, LA or NY and other places like Germany. Considering that already many MK fans travel to the RAH to see him play live, he doesn´t have to tour, just book the RAH for a week when he wants or can...