From the forums and how long the thread has gotten to that blog post, and how negative the majority seem about it, I can see them reverting this proposed change. My opinion it is a dumb idea, and will cause more fail-tanks queueing, as well as increase resentment among pure DPS vs hybrid. About the only thing that they could change to make me somewhat support this is if they made the rewards bind on account, but that still doesn't solve the case of fairness when a person only has one character who is a pure DPS class. Blizzard also hasn't thought of the case of partial groups queueing, and infact this system will encourage tanks and healers to not run with groups/guilds/friends just to farm these. It should improve DPS queue times, but I don't expect it will be by much, especially after the first week or so, as tanks will collect all the mounts/pets in a hurry, or the drop rate will be so bad, that they will give up on queueing.
Tanks/healers already have a reward for queueing - fast queues, and faster rate of acquisition of points as a result. I've seen lots of tanks in randoms who die or cause a wipe due to their own stupidity (grabbing more mobs that the healer can heal through, standing in bad stuff and blaming the healer when they die, breaking CC and then blaming the CCrs when they get killed) and then rage quit, or call everyone else fail. And who can forget the tanks who don't like the instance they get in and drop group at the start, or drop group after one wipe.
Now, there are statistically more fail DPS in the queue than fail tanks, but the vote to kick feature could, and should be used as a filter for this. Most of the issues with the current Heroic queues will be solved as people get better geared, i.e the next tier, where everyone but new characters will outgear the heroics, and as such everything will become more like wrath of the lich king with AOE everypull. If they want to encourage more geared and experienced tanks to queue, they could probably do something about repair bills (i.e. make epics as cheap to repair as greens) as well as increase the gold from completing the random instance.