Regarding Multiverse -
So, my best guess would circle around 2019 for the eARC - maybe 2018 with very much luck.
Hell's Gate October 2006
five months later
Hell Hath No Fury March 2007
nine years later
The Road to Hell March 1, 2016
So MAYBE book 4 won't be another decade behind book 3 -- or maybe it will.
The gaps wouldn't be bad if these were actually novels in their own right. The early books in most of his series were able to stand alone, but more recently each "series" is one big book just released in pieces.
Compare most of the Honor books, where you can finish reading and close the book, then look at any of the Safehold or Multiverse books where you hit the last page and you know you haven't finished reading anything.
Cliff-hangers are fine for a TV series but not very satisfying for books, especially when you can't be sure when or even if the next book is coming.