The 399 rumor started from hidden numbers found in their ad.
If it is 399, I wouldn't be surprised. Microsoft is probably willing to take a loss to try to catch up with PS4 but I don't think it will achieve their dream because Scorpio faces a lot of problems.
It is supposed to be a mid gen upgrade instead of a next gen system which means it is held back by Xbox One. It is also late to the party. Older games that don't get updates may still run better on PS4 and the new games that receive updates will probably be like the PS4 Pro. If PS4 Pro support indicates anything, I think many people are just waiting for a true next gen system like the PS5 which may launch a couple years from now.
Scorpio will be for the diehard Xbox fans that probably bought the Xbox One at launch and Xbox One S last year anyway.
