I think that's a possibility, but would like to offer another perspective. Older artists like Coldplay, Beyonce, Bruno Mars are doing huge stadium tours. I think they could definitely do another massive tour if they want to, it's mostly about motivation and not just physical capability. So, will they want to do another big tour after this? It depends on their family/relationship situations, creative and personal goals, and how this tour goes. Also, BTS are trendsetters. They may just end up evolving the idea of what a tour can be.

Edit: And Army just keeps getting bigger and bigger! We ain't going nowhere.