I dont think they will change it neither as its already said on this forums, its a matter of money and they wont stop 1 player for paying 2+ accounts, actually i think they anytime soon will make the ability of 6 man party so we can 6 box instead of 5 box:P (joke aside)
There by after last 4 years of raiding, pvp, arena and doing more or less all instances in game multiboxing has become a new challenge for me, if they somehow remove that ability i dont think wow would be of my interest anymore, and probably many ppl would have it that way...wtf i cant play my accounts anymore...i mean, they even implement faction change for getting more money, why would they ban us, their best costumers?