I don't think they're going to go down but that's a really weird thing to say since They've not made any signings yet this window This is only speculation, I've not seen it anywhere particularly reputable Shackell is past his best and 34. He won't last the pace to play every game. Expect he wants high wages to boot. Derby are linked with Gregory, so this deal may be part of an exchange which Millwall come out much worse from So on balance I'd say signings and windows like this are what might leave Millwall unstuck, if assumptions are true.
Good player in his day. Enjoyed watching him for us. Cool head and good allround ability but wouldn't welcome him back at 34.