So they'll let you use the 14 then swap the '14 for a '15 for $2,500 including all the options you were supposed to get??? I'd make sure its all spelled out VERY clearly on paper with any mileage, wear and tear, condition restrictions clearly spelled out. If salesmen change, GM whatever, without this all in writing it's all here-say. They screwed up once so it can happen again.
I can see the forum header seven months from now "dealer made me buy the wrong car but promised to trade for nothing and now has no recollection of the deal so now i'm stuck"
I'd want it in iron clad writing acknowledge by the owner/uppermost management JUST IN CASE.....
If they're suggesting something different, like we'll re-order it, it's 7 months away and $2,500 more than we quoted I'd make them eat the $2,500, its their mistake, not yours, you should not be penalized. LRNA, BBB, local news could be valid threats/actions to take if they won't play ball.