I'm not so sure about Warren even though she was the person I liked most in the primary (although I couldn't vote for her being registered as 3rd party). In addition to her age is the fact that she would have a replacement chosen by a Republican for up to 6 months - and you just know they would insist on all 6. Those would be the 6 months Biden would need the most to get anything done, the 6 months when his political capital is likely at his highest. Losing Warren in the Senate could be a disaster - it's going to be close no matter what, and I'd hate to see the political appointee who replaces her for those 6 months be the vote that enables Mitchocrite McConnel to keep his job.