I think it also depends on the ideas of his Management, the tour-promoters, organisators and on Mark. Surely, he also can play a "smaller-location-tour" with smaller venues around 1000 seats plus or minus, than he can fullfill the ticket-demands for smaller locations, if he plays some venues twice. I´m not thinking of bigger locations with 10.000 plus seats or something like that, but the possibility of a tour in EU and USA with carefully chosen smaller locations. It´s an idea. Maybe it can be realistic in case of his health-shape, the effort in case of planning such a tour and, of course, the demand of us fans, the ticket-purchasers.
It also depends on Marks decisions, how his worldtours look like in the future.
I hope, that he will be in very good shape in the future and that he can realize tours in the future and it doesn´t matter how such a tour looks like in the future, with smaller or bigger venues.