Your current Xbox career will also carry forward onto the next-gen console.
Along with offering backwards compatibility for previous generations of Xbox, Project Scarlett will also support all existing Xbox One controllers and peripherals. This was confirmed in a recent Xbox Wire post, which also noted that your current “Xbox career” would also carry forward. Support for existing Achievements and social contacts seems to be included but more explicit confirmation is needed.
Meanwhile, on the recent episode of Inside Xbox, Xbox boss Phil Spencer outright confirmed that Xbox, Xbox 360 and Xbox One titles would all be playable on Scarlett. Much like the current backwards compatibility scenario on Xbox One, not every game will be supported due to licensing issues and whatnot. But that’s still a pretty hefty library out of the gate for Scarlett.
Project Scarlett will be releasing in Holiday 2020 and utilizes a custom version of AMD’s Zen 2 CPU and Navi technology. 343 Industries’ Halo Infinite will also launch with the console though it’s still coming to Xbox One and Windows 10 PC. Stay tuned for more information on Scarlett in the coming days (and year).