It sounds like a marketing strategy that Ford tried to use with the 2003 Mach 1's. I had to pay full MSRP because only the large Ford houses got one, and I mean one as in a single Mach 1. They later manufactured a bunch of them.
Ford also announced in 2003 that the Mach 1 was only going to be manufactured in 2003 and not in 2004. That turned out to be a lie. I wouldn't trust anything Ford announces. Again, it's a marketing strategy. Most likely if most of those Mustangs are sold by May, Ford will keep pumping them out until the market starts to slow, then cut off production. They are in the business to sell cars, and if Mustangs are selling, then they will keep producing them.