Very sorry to bump this, but I had a bout of nostalgia for Momodora IV and subsequently happened upon this response from developer rdein on Twitter:
I meant "Momodora V" is no longer in development, and it really isn't. I'm making another game now. Not related to Momodora at all
09:44 - 26. Juli 2017
This is more recent than the bitsummit video we have of the game, but I cannot find any more info on the possible cancellation even on his Twitter. Can someone shed some light on this?
He reopened the Patreon and has been doing updates on the new game:
https://www.patreon.com/rdein
Essentially the previous video has been made into a different game called Semilla (project name subject to change). Thematically it's similar to Momodora games but I think partly he's separating it out because of the move to 3D but he's also stated in updates that it's been fun having the freedom of doing whatever he wants with it not being tied to the existing series.
I'm not sure how appropriate it is to take locked Patreon updates and share the posts but here's a chunk from the first update when he reopened the Patreon and started sharing details:
"The game is a 3D "action-adventure" style game, being made in Unity. This is the first 3D project we've ever worked on. My main inspirations for it are the Zelda series and Souls games, and I'm aiming to make a game similar to Momodora: RUtM, except in 3D. A bit like a "Metroidvania", meaning you can go back and forth between areas in a non-linear fashion.
It's worth noting that this game is not part of Momodora. It's a completely new setting, with new characters.
The game is set in a fictional account of the european dark ages, especially the inquisition time. You play as Semilla, a nun forced to do clerical service, who is on a mission to purify the heretics that threaten the people and the princess."