1) I see no reason to "shy away" just because they're changing it into something called the Edge. It's not like you won't be able to get parts for it, or anything like that.
2) The best deal is the lowest available price on the one that YOU like. The lowest price will be on the last one available in the USA, about 2 years from now. Is that the "best deal," if you and the family hate the color? Or if it doesn't have the right options? And in 20 years, I don't think I've ever seen a "best-time-of-year-to-buy" time frame. Christmas Eve, when there isn't a customer to be seen? Maybe, but there are just too many variables to say accurately.
My dad bought a 05 Freestyle in the summer. It was a demo with 6,000 miles on it so he got a good deal (this was before Family Plan Pricing started). He really loves it and finds it handles as good in the snow as his Subaru Outback did.
From all I've heard, the Freestyle will become the Mercury Magellan. At the same time, the Ford Edge will be introduced so Ford and Mercury will actually have two different crossover SUVs to offer. Further, the Freestyle is mechanically similar to the Five Hundred/Montego. I don't see any issues with it bei9ng supported in the future.