a product moving exchanges doesn't happen that often. tf moved from cme to ice in june 2007. when a product moves volume can dramatically drop off - esp if there are extra data feed fees to pay now and/or the other exchange starts a huge marketing push for their own comparable product although the s&p small cap futures are still very lightly traded.
if cme really wanted to stick it to ice they would have done what they did in the rates side of things whenever a competitor like elx tried to muscle in on their monopoly - lower trading fees dramatically until their competitor gives up then raise the fees back up lol.