I'm living very much in the hope that if he steps in it will be for the tournament rather than a someone quitting his current post. In all honesty I don't see why not, he's not a bad pair of hands for the national team, I'm sure he would want to do it and if it was just for the month or so then it's not bad news for Newcastle (players aren't training and purchases/ sales are done mostly by the club anyway plus it would raise our profile by association).
Sounds like they aren't appointing for now but I do hope they get to semi-finals or final so they give Hierro a shot rather than knee-jerking to a "safe pair of hands" like Rafa if they go out in the group stages!