I'm trying to dissect some of the information about these two sets.
http://magic.wizards.com/en/MTGO/articles/archive/magic-online/announcing-legendary-cube-2015-08-05http://wpn.wizards.com/en/products/commander-2015The commander 2015 set will have 55 new cards in it, and the Legendary Cube Drafts on Modo will pay in prize packs that include all 55 new cards. The commander decks will not be sold online, and the only way to get the cards is from those prize packs. There is one legendary card reprint in the prize packs that is also in commander 2015 (56 cards).
There are a handful of Legendary creatures from Legends that are not currently available online like Johan, Ayesha Tanaka, Gosta Dirk, Kasimir the Lone Wolf, Lord Magnus, Tolaria, and Ur-Drago that I expect to see in the prize packs just for the sake of completion. There are still some straggler cards not available on Magic online like Niall Silvain and Golgothian Sylex that have almost no real world applications, but I would think for the sake of completion, Wizards will need to find a way to add these cards eventually. ***
I digress, the point of this post is to have other people looking at this information and see if you come to this conclusion:
ALL THE NEW CARDS IN COMMANDER 2015 ARE LEGENDARY.
that's how I'm inferring the information, and to be honest, I hope that I am wrong.
*** (There are a substancially large number of bad cards from the Dark, Ice Age, Homelands, and Fallen Empires not available online, as well as many stragglers from Legends, Arabian Nights, and Alliances that the prize packs could not contain all these cards and all the new commander cards.)