I think the chances of the "iPad mini" coming out with more than 8gb/16gb of space is unlikely, as such I would not get one.
I already have a motorola xoom 32gb, iPad 3 64GB and Kindle Fire, I really can't justify getting another 7" tablet.
If I were to get another 7" (or 7.85")tablet it would likely be the Google Nexus Tablet 16GB because the lack of a file system support is a HUGE drawback of the iPad in my opinion.
Even then the Nexus lacks external support and the operating system takes about 1.6GB of useable space away from the user meaning even getting the 16GB I'd have a anemic 14.4GB of useable space.
I was really hoping they'd add some sort of file system into iOS 6, but alas they continue to cripple what could be so much more than it currently is. Don't get me wrong, I love the iPad but the lack of a file system is a huge drawback for me and is the single biggest reason I use my Xoom more than my iPad.
I'm sure the lack of a file system is a cheap attempt to get people to sign up with their cloud service but the cloud service is never going to be as reliable, as quick, as secure as local storage.