In terms of actually going to all the different areas of the zones, that never happens in the MSQ. A lot of it is for sidequests and after you've done all sidequests, the entirety of each place in the game is pretty much explored. If you're not into sidequests, that's fine, but you'd probably be complaining if they merged sidequests into the MSQ, so.
As for "running out of places to go in the MSQ", I don't think this will happen because we have:
- A number of shards we can go to.
- Corvos, the garlean territories and Blindfrost.
- Meracydia.
- The past (Yoshi-P mentioned this, but I've thought it as well because a lot of interesting stuff happened in past calamities). But it would also create a chicken or egg first situation as time always does and that's the part I don't like.
Given they are only planning for "the next 10 years", they don't need a lot of places to remain unless they want to plan further than that, because they can only fit about 3 expansions into the remainder of that (now) 9 years with their current schedule.