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Project Helix, the next XBOX console, is not expected to feature a disc drive
(news.instant-gaming.com)
This is a most excellent place for technology news and articles.
I don't use steam, but I did a quick search and I don't see many articles of them removing a game you've paid for from your library without giving you a refund. Even then you can add games not paid for on steam, into steam so I'm not sure your point. You can add a disk game into steam.