Richie could easily sell out a theatre tour (Shepherds Bush size) in Europe, especially promoting as a Richie solo show playing his albums and BJ covers. As already mentioned, making money off of it is a whole different kettle of fish, but the popularity is there: most people outside of this fanbase wouldn't have seen the drama and recent shambles and he does have a lot of goodwill with rock fans. Festivals and theatre shows he'd have no problem selling well (price dependant of course, but Shepherd's Bush and Islington went very quickly).