Interesting. I looked up articles on the RFP for up to 200 airframes:

Delta's fleet strategy under scrutiny after RFP on narrowbodies | Centre for Asia Pacific Aviation - CAPA

Look at the list of manufacturers that received the RFP. Granted, I doubt we get anything from China or Russia, but they did write to Canada and Brazil. I'm not saying I'm ranking the RFP much higher than a rumor, but it certainly is an expression of interest in aircraft around the 100-145 seat range, at least in the case of Bombardier and Embraer.

Then again read the comment about "testing the waters".

Overall, I don't think it matters whether the company tells us they do or do not want 100-seaters: we just need to maintain or improve scope restrictions in case they do. Whatever they do, we'll read about it in the paper.