Turns out that Hasbro has not sprung an already published games on those in Essen, but is instead demonstrating the aforementioned Magic: The Gathering Strategy Board Game for fairgoers ahead of a scheduled release at Gen Con 2015. A short description of the game, of which Craig Van Ness is the lead designer, is Heroscape + Magic: The Gathering, although that's not entirely accurate in its briefness; for a longer description, I invite you to watch this video.
Update: The base game for Magic: The Gathering Strategy Board Game will not be collectible, but contain fixed components and be designed for 2-5 players. No plans have been made for expansions (other than that they might exist) and whether or not they might consist of collectible elements. All of those decisions are still to be made, and Hasbro is asking those who demo the game to complete playtest forms and provide feedback on the experience.