It's a toss up between the first two answers. I don't upgrade to each new device version each time a new one comes out but rather look at the attributes of the new version and decide if there is enough benefit to me to be worth the cost
I was perfectly happy with my ipad 1 in most respects but the cameras on the ipad 2 were a compelling enought feature for me to upgrade. I did not purchase an iPad 3 or 4 as I don't feel the trade off between the retina display and its cost in terms of procssing heat and battery are worth it to me.
Unless there is some breakthrough in these costs of a retina display, I would be LESS likely to purchase a retina mini. If they figure out how to deliver similar performance and size and weight and battery life and charging time in a new mini with a better display I'm all for it.
For now I love the form factor and functionality of the mini. I was happy with the iPad 1/2 screens and while the retina is clearly a superior screen in terms of resolution and fidelity, the mini screen suits my purposes just fine. A lot is going to depend on your usage patterns and personal preferences.