The all access thing is not new, and has been available from Gamestop since XSX pre-orders went live. And Gamestop also participated in last years All Access deal MS did.
They also sell Playstation payment plans through 3rd party services...
MS is selling Gamestop software, probably giving them a really good deal, hence the word "strategic". Why? Because MS actually wants Gamestop to not die.. so they might be giving them a better deal than they are other companies. MS benefits from Gamestop being able to sell more software... so does Sony, there is zero chance Gamestop would take some sort of deal that discouraged them from selling the dominate market leader's products.
These are both publicly traded companies.. Gamestop can't make some secret shady deal to do more business with MS than Sony without it being known, and the entire concept is ludicrous at face value.