What happened with Jeremy Soule and those allegations?
I assume he won't be working on ES6

He's been MIA for years now ever since those allegations. I highly doubt Bethesda would bring him back.

Shame. He was the video game industry's Hans Zimmer or John Williams for so many years.

Turned out to be a creep but Bethesda would own Oblivion's music.

Inon Zur will be doing ES6.

I think The Elder Scrolls Online composer should do ES6 though, as he has more experience with the ES IP.

ESO High Isle Theme has me like...

Maybe get Malukah in as well.

Was it ever proven though?

I know not likely, but Bear McCreary would be a good choice to do the soundtrack for The Elder Scrolls VI. 

No but it's irrelevant at this point as Bethesda cut ties, Materia Collective cut ties and he has vanished off the face of the Earth, along with the multiple allegations, he never delivered on a Kickstarer which raised $120k, the dude was torpedoing his career even before these allegations came out - Years of Delays, Fake Updates, and "Troll" Accusations: A Popular Composer's Kickstarter Symphony : r/HobbyDrama

TLDR is that he ran a company in 2007 called DirectSong that sold musical expansions for videogames like Guild Wars, he repeatedly failed to fulfil orders and received an F rating by the Better Business Bureau. He raised money on Kickstarter in 2013 to create a symphony then ghosted everyone for years and then forced into refunds. Then got into a legal fight in 2016 between him, his brother and a group of investors.

He stopped receiving work in 2017 for the most part (before the allegations) so the allegations weren't really the thing that destroyed his career but rather, they were just the last straw in a series of problematic stuff from him and I'd not be surprised if even without the allegations he became a bit of a Marty O'Donnell (no longer receiving major work).

Better for everyone to just move on because he's never coming back to Bethesda.