I think the financial impact due to the loss of many multiboxers is overstated... and I think this played into Blizzard's decision to take action..
Most multiboxers were essentially free to play players... they used tokens to pay for their subs and expansions... when a free to play player stops playing Blizzard losses nothing...
Most people would argue... someone is buying those tokens for $20... but that's still going to happen with or without multiboxers playing..
There is likely to be some impact based on the idea that multiboxers buying lots of tokens for game time raised the gold value of the token which causes more people to buy tokens....
We don't really know the mechanics of exactly how the tokens work so we aren't really sure how much of an impact this will really be...