Via The Verge, Mozilla says this is what it will be putting in the Terms:
You give Mozilla the rights necessary to operate Firefox. This includes processing your data as we describe in the Firefox Privacy Notice. It also includes a nonexclusive, royalty-free, worldwide license for the purpose of doing as you request with the content you input in Firefox. This does not give Mozilla any ownership in that content.
I wasn’t sure how to feel about it initially, but that does sound a little better. However, I do believe the whole thing should be reverted to what it was prior, because it still does not explicitly rule out selling user data to third-party advertising firms or nefarious actors. It’s too ambiguous, in my opinion.