I'm guessing most of Flex sales at this point are fleet sales.
Maybe a lot, but certainly not all. More important, it remains relatively popular on the west coast, where other Ford non-truck models remain scarce (save the Mustang, of course). Better to sell 20k a year, some of which is to consumers, than to sell 2,500 a year to fleet only.
Honestly, I don't know how it's going to be cost-effective to keep the line going for such a small number. Nothing about this decision makes any sense to me.
Current Car: 2013 Lincoln MKZ Hybrid Reserve Ice Storm 2.0h CVT
2008 Ford Focus SE Sedan White 2.0L Duratec I4 4 Speed Automatic
2004 Lincoln LS V6 Luxury Cashmere Tri-Coat 3.0L Duratec V6 5 Speed Automatic with SST
1999 Mercury Sable LS Premium Toreador Red Clear Coat Metalic 3.0L Duratec V6 4 Speed Automatic