Well, we don't really know what the new iPad Air will have, but it will have to be really groundbreaking for me to upgrade this year. I've upgraded to every model of iPad since the iPad 1, but with the iPad Air I finally feel it's mature enough to last at least two years.
It's also going to depend on what the iPhone 6 does; which I will upgrade to this year. If Apple can talk me into a significantly larger iPhone, it's going to take over a lot of the tasks I carry an iPad around for; making upgrading the iPad even less important.
I'll have to have one in my hands before I can decide on the iPhone upgrade path.