I personally really hope that the old PvP gear has rating requirements on it, either rbg or arena, I think they should have the same requirements they did back in the day they were current, the gear was intended for people who were good at pvp, I like to walk around in PvP gear and as much as I like some of the old sets like Wrathful or s3, I don't want to wear it if every idiot is going to wear it because its shiney. It probably wont have rating requirements on it because Blizzard has always made PvP stuff accessable to PvE'rs and not vice versa; if I want to wear t10 gear, I have to go do the t10 raids, if some idiot wants to wear the any of the season arena gear they should have to do arena - not just the same BGs they have always done, and they should have to do reasonably well at arena, I mean come on; its not that difficult to get 2k for some shoulders!
I just think that transmogrification will take some of the progression out of the game and if they want to keep the game fresh they need to make the items that look best, hardest to get. Getting a full pve tier set will take a very long time (there are small drop chances on the pieces, you have to hope its for your class and then there is a week lock out - it will take atleast a few weeks even if you're very luck.), PvP gear on the other hand if it is made totally accessible for every one with just honor then it will be the easiest thing ever!
An alternative idea is that you could buy the gear without rating (so that the leveling people can buy pvp gear for their level) and can buy for honor; BUT - when you put it into the transmogrification window it says "requires a personal and team rating of 1800 / 2000 / 2200 (etc)", that way levelers / rp'rs can still buy and wear the gear, but if you want to wear full s8 in arena or bgs then you need to have the relevant rating pre-requisites.