Yes, I think they will. On Ebay yesterday there were quite a few German offers of it at around £42-47 which were not there only a few days ago, so I guess they are overstocks or a few more sets have been printed up to assuage demand. The Bobbie Gentry box set sold out in a couple of months as of last Novemeber and Universal printed up (or are currently doing) 350 or so extra copies for late comers, so I guess this might be happening with Mott as well.
Incidentally, I have read that disc 6 in some of these Mental Train sets has the track cues in the wrong places, has anyone who has the set already found that to be the case (like track 2 having the first part of track 3 in it as well before the track number changes)? Others have said there's nothing wrong with theirs, so just wondering. The same thing happened with one disc in the PIL set I bought last year but Universal replaced it with a good copy.