When they did this before, most of the areas with the super high leveled mobs were generally just ignored and avoided outright. Sure some people would go over and press their luck but the majority wanted nothing to do with it. FFXI had this before too, though not so much these days. The areas in the zones with the higher than usual levels were simply not explored.

That said, do not be surprised if they do something like this for this upcoming Sightseeing Log, since you have to do an emote to finish some of them apparently. "Brave a dangerous area to discover a stunning vista!"