If Rafa signs, I would put our chances of promotion at 80%. This is partly because he is a good manager but also because it would mean that he has been promised resources. Also, players will stay with us/sign for us if Rafa is in charge that wouldn't with someone else in charge. If we get Neil Warnick or his like, chances go to 50/50. And if we don't get promoted in the first season, then the Championship can be a hell of a league to get out of.
I think it more or less all hinges on Rafa staying. He stays, better players stay/come into the club, the optimism remains, the fans get behind the project, it should all go quite well. George Caulkin of The Times is among a number who think it's very likely.
He is clearly considering it, so if it doesn't happen it will mean A. some very big club makes a swoop, or B. we ****ed it up