Xbox One is getting a HUGE update. Starting with preview members (who can download it today), we can expect 360's games on Xbox One.
This is a step in the direction of removing the online support from 360 that we've been waiting for.
Here's the catch. Your gamertag must have played on that title to be able to download and play the 360 title. That isn't exactly inportant though, as you will only go for the select few that you miss playing from last gen.
This could also signal the end of "HD remakes" and that is something we can be happy with.