ME and CO are flipping for sure. AZ is probably flipping too. But remember Dems will almost certainly lose a seat in Alabama.
Montana is definitely a possibility. I could see democrats getting to 50 or 51. Of course that won't mean much due to the filibuster but at least it ensures decent judges, replacing RBG (if she can survive until January) etc. Biden isn't going to end the filibuster but he should if he wants to govern. Trump may be gone in January but it'll still be his Republican Party. That shyt is not going away.