Well the new 8 man dungeons would end up being the new raids. Just wouldn't be like it is now just with a single boss fight. Something like AV, cutters cry & Darkhold was in the 1.23b. First Coil was so so but then they just started with just direct boss fights. Raids are actually dungeons, not how xiv calls them. There would still be endgame content. Players would just have to plan out how they did a dungeon and how they defeat the boss on a raid scale, something more complex dungeon wise like the first coil turn.

In terms of the flying, yes it ruins the exploring aspect of a game once you have the ability to fly. In next expansion I hope they had boats as the next new form of transportation & having the zones be the same kinda size as ARR zones are. You would still have the option to ride chocobos, go on foot, or ride your boat on lakes or rivers or part of the ocean till you hit a invisable wall. They aren't going to ever add flying to ARR zones so its not that big of a deal not having the option to fly everywhere. You wouldn't expect all flying mount to dive underwater would you. On foot, on air, on water, underwater, in space. If the next expansion is a underwater expansion then it will probably not need the option to fly.