"Oh no, not again?" I don't see the connection.
Happened to me that I created new topics which have already been started, but are on page 4-5-6 of the Nintendo thread. And I did it again, so that's why 'Oh, no, not again!'

Anyways, that topic was about "games you'd want to be made" and not specifically "PMD3".
YOU ARE FORGETTING SOME DETAILS!!
Chunsoft could be having a nice long break from PMD games because their previous one didn't work. Shortly after PMD 3 (Explorers of Sky), they made three PMD games for the Wii called:
Pokémon Mystery Dungeon: Keep Going! Blazing Adventure Squad!
Pokémon Mystery Dungeon: Let's Go! Stormy Adventure Squad!
Pokémon Mystery Dungeon: Go For It! Light Adventure Squad!
They didn't go so well and weren't localised due to this... Check out Serebii.net for more details!

Well, yes, I knew about that, but their content is VERY short. 15 dungeons each. That's all.
These games each have 15 dungeons each and so can be seen as fairly short in comparison to the other Mystery Dungeon games.
I mean a new PMD for DS (or 3ds). Or
at least localizing those three.