I don't know why Apple would want to have a retina mini and non retina mini 2 out there. I mean, from a pure pride position, being proud of producing the best device you can, a mini with retina, then settling and releasing a cheaper, non-retina option-- inferior display... I don't think they need to do that. They've always said they don't release cheap products, removing features, simply to hit a price point. They say the strive to make the best products in the world. A new mini with non-retina screen isn't the best product in the world.
Of course, eventually every Apple product will have a retina screen, and how much of a hit in the wallet Apple wants to take to get us there as quickly as possible is unknown. But if I was Tim Cook, I would not release an inferior product along side a retina mini.
I have a mini, love it, and am waiting for a retina version. Once I get a retina mini, I may hold off on upgrading it to a new version for maybe 2-3 cycles.
As an aside, I always updated my MacBook Pros almost yearly. However, my retina MBP has all the technology I really need. Retina screen, USB3, Thunderbolt, SSD, SD slot, HDMI, 8GB RAM, etc. This will be the first MBP I've taken through my entire AppleCare. I don't plan on getting another MBP until June 2015, when my AppleCare plan expires. I expect the same will happen with my next mini. Once I have that great screen, and for what I use it for, I'm sure it will last me at least 2 product revisions, maybe 3.