There is no sort of guarantee that this new Shelby is a collector car. I could say the same thing about my 1994 B4C Camaro. Since 1991 there have been less than 4000 B4C models built. For 1994, there were 668. Technically, I could say that mine is 1 of 668 and it should be worth a gazillion dollars, but it's not. It's just a conversation I enjoy having, and just telling people, "Hey, I have a rare car and it's 1 of 668 made."
The 2003 and 2004 Cobras have a better chance of becoming collectible than the new Shelby cars IMO. They're the ones that "wow" people. Not only did they not weigh 4000 lbs, but they had strong blocks that were stock with 390 hp and could easily be upped to over 500 with little to no effort, plus they had the IRS setup out back. The 2003-2004 Cobra is the best performing Mustang there ever was; period. It doesn't matter that the new Shelby is faster in a straight line.
The new Shelby cars are very nice, and I like them, but as far as recent Mustangs go, besides my "2010 wet dream," the sun rises and sets with the 2003-2004 Cobras for me.
Anyway, before I get too far off the beaten path, go to a dealership and make sure you have a video camera, because I want to see their reactions when you go to them complaining about a few brackets with surface rust on them. I'm sure it will make for good comedy. They're going to laugh at you, pat you on the head, and say, "Okay, you can go now. Come back when you really do have a problem."