Hi @fpaiano,
You can pretty much get back the "old" discussion view at this point by setting the default thread state to expanded and the sort order from oldest to newest in the discussion settings, then choosing the inline view as you're reading the discussion. I was never a fan of the split screen (a.k.a. sidebar) view myself with the new discussion preview either when it was basically forced upon everyone. Now that it's an option you can select as a user, I do think its useful for users who do actually prefer that view, but also lets those of us who prefer the "classic" view to have that too.
-Chris