either this is off to the west of equestria where g4 maps cut off, or the g5 staff didn’t bother to look at even the map to create a plausible location for these.

Here’s hoping the show will feature just as much, if not more exploration. I’ll be very sad if there are truly only three locations compared to the multitude. What did the ponies do, nuke themselves?
 
Maretime Bay seems to be the successor of Horeshoe Bay.
 
And if Zephyr Heights is a successor version of Canterlot, then it would make Bridlewood either in the Everfree forest or the Hollow Shades, given that the unicorns live somewhere between the Earth Ponies and pegasi.
 
Which leaves a whole lot of Equestria to explore! And it would be awesome to see Equestria rendered out in full 3D! We already got to see some gorgeous locations. Unfortunately, the fact that the show is 3D is probably going to be what limits exploration.
 
As it stands, with only three known settlements the pony population has plummeted. I’d guess their population is max 40,000 - 50,000. Zephyr Heights looks to have the largest population with the highest quality of life, Martine Bay with a medium population and coinciding quality of life, and lastly Bridlewood with the lowest population and lowest(relatively) quality of life.
 
If there’s ONLY three pony settlements left, what happened?! A war?