where did you find this out?

link
And there's also an article about it at the Winchester Family Business. But beware, there's more spoilers :)

I still feeling a bit unsure if this is the way to go but if Jeremy is trying to get the vibe of Season 2 and 3 back then it is the way to go. However, seeing more of purgatory would of made more sense hence it has such potential. All of us just need to keep cool and keep an open mind, anything could possibly happen this season and finding out what it is, is one of our jobs :)

What a bummer. After last season's brilliant cliffhanger, this feels like a huge cop-out to me. I thought we'd get to see Dean explore Purgatory for a couple of episodes, at least.

I agree with josch, I'd like to see what happens in Purgatory. But maybe it can be cool this way... I'll have to wait and see. Perhaps we get to see something about Purgatory in the flashbacks...