This is the first time someone has done a good job of drawing out the expected effects of trading, in my opinion. I'd like to respond to some of the points made by Logress, here.
-Free players would be even more like second class citizens, not being able to trade.
For the most part, this seems true. However, as noted below, people who spend a little will have a lot more options. In other words, trading would provide an incentive for people to spend a little whereas, right now, buying just one box won't likely do much for a player. So, I believe trading would result in there being less players who spend nothing. A great deal of us don't spend only because one box won't do much for us, if it does anything at all. On that note, I'd like to say that I'm considering spending $8 on two more EX packs - the first cash I've ever spent here. It's because the EX packs are color specific and I already know which cards I'm getting... ones that I want. So... there are clearly other ways to get us to spend a little aside from implementing trading. Color specific boosters still looks like a good idea to me.
-"Veteran" free players who've been around for a long time and slowly accumulated their cards may become extinct.
I'm not sure why you believe this to be the case. I'm a vet. free player - I have one fenrir, a succubus, etc., and I play gowan. With the implementation of trading, I'd be able to get rid of all my decent cards in other spheres that I'll never use for good gowan cards. I see no disadvantage for Vet. free players, here, or any veteran players, for that matter - even people who have spent a lot of cash. The more cards one has accumulated, the more trading power one has.
-People who buy a little will have a lot more options open to them. They may not find it much easier to build on-meta decks, though.
-People who want to have complete collections will find it A LOT easier. (note, as we have said many times, we recognize that it's too difficult even for a wealthy collector to get complete sets right now, and we have been working on it. As great as it is for our cashflow when someone gets really frustrated at having 3 of every card except one of his rarity 5's which he only has 2 of and flips out and buys 30 boxes trying to get that one last card, we understand if that happens every expansion our users' minds will eventually snap like twigs and they will hunt us down and kill us in some grusome way involving a bag of rusty nails, a . We have approval to do a Point Card system to alleviate this, and it will be implemented as soon as we can iron out the details -- before set 3, at least.)
It's good to hear that there is a solution for those who want to collect certain cards without spending an incredible amount of cash. Of course, if it works out, there's even less of a chance that trading will be implemented; one of the problems that trading solves will no longer be a problem. I'm not sure what the point card system will do for people who may want to buy a box but are scared of not getting the cards they want, hence wasting their money (I fall into this category). I can't wait to see more details on this new point card system.
Light thinks it travels faster than anything but it is wrong. No matter how fast light travels, it finds the darkness has always got there first, and is waiting for it.
-- Terry Pratchett