Standard Packs?

I have quite a lot of (unopened) standard packs. I am wondering what will happen if I keep them closed until rotation. Will they become "new standard" packs or will their remain with "old standard" ? any idea?

They will give u next standard cards after the rotation, which will include: barrens, united, alterac and new expansion. In resume, they will always give standard cards, no matter in what standard we are.

Sounds like  a decent idea to keep them, I haven't though of that.

All packs pull cards based on when they are opened, not received

So Standard Packs are able to contain new expansion cards even if they were received before the expansion

Expansion Packs are able to contain their mini-set cards as soon as the mini-set is released

etc.