I read that we'll all be getting a free retcon when the new economy kicks in, but I still haven't used my last free retcon. Anyone know if the newer one would replace my old one? Is it a use-it-or-lose-it thing or can I just wait and carry multiple free retcons?

It will replace your old one, so you can't have more than one free Retcon at any character at any time.

I came in here expecting another WoW thread. I'm so dissapointed. (I think you mean hoard) ;)

But seriously, yes you can only carry 1 full retcon at once, as per a dev post that I don't have a link for at the moment.

hoard
a supply or fund stored up and often hidden away

horde
a teeming crowd or throng

So use it up now. Try some interesting stuff with your build. In a few days you get to retcon all over again.

I dare say this will probably be the second in a long line of retcons. They'll have to do it with every change which could potentially mess your build. Which happens a lot in MMO's!

0 + 1 = 1
1 + 1 = 1

You get one free available retcon at any one time. No bonus for hoarding.

Both the Horde and the Alliance will get free retcons. But you can only hold one at a time. Use it or lose it.

But what if you want the Horde to have free retcons too?

My problem is i'm paranoid they will not give another free retcon if I use mine now.
I know they said they will be, but its not on test with the newest patch so I wonder...

There isn't much reason for them to specifically give free retcons to characters on the test server.