I don't really know enough about corp hospitality sales to answer with much authority but I'd imagine a not insignificant portion of anticipated additional income from that source would have been of an ad-hoc/ non repeating nature rather than annual. Certainly the couple of times I've gone to events as that sort of punter the companies I've worked for did it as a one off treat for staff at fairly short notice rather than holding a box for a season.
How much all this will cost ultimately comes down to how many games we were expecting to play there. No idea exactly where I got it from but I had the expectation that we'd be in from October at the latest. If that ever was genuinely the case then it's potentially 14 odd home games where the additional revenue would be lost.
If the revenue uplift from that number of games isn't significant enough to justify moving mid season then we really do have problems given the costs we've incurred in getting that extra capacity.
If the plan was for a move later in the season then it's obviously less of an issue.
Either way it isn't the end of the world. Big projects get delayed fairly routinely and you'd assume that risk was factored into the investment decision. I just think it's a bit of a stretch to assume this is a decision we are making voluntarily and happily as the press release would suggest.