I don't see the 6D hurting the 5D MIII as the 5D MIII is a more advanced body. However, I do see the 6D affecting the 5D MII and would be surprised if it continued much longer but it sounds like Canon does intend to keep it around for a while so we'll have to wait and see. As far as 5D MIII pricing, as of November 1st Canon put in place MAP pricing for all authorized Canon dealers which is the $3,499 minus any rebates Canon has on the body. You will see other stores advertise below this price but they are not Canon Authorized dealers (and if they are Canon will probably catch them sooner or later), supposedly they still come with a warranty and everything so technically there shouldn't be a risk purchasing from them but as with anything it's a gamble. Should these non-authorized stores continue to discount the bodies heavily I wouldn't be surprised to see their shipments from Canon to start to shrink in quantity.