Well it seems logical because.
A. All Xbox One games are treated as if they are digital copies.
B. Xbox One games can be shared or given away.
C. Therefore Xbox One digital copies can be shared or given away.
I think Microsoft clarified a lot of this here. On the giving games away it is very clear:
Give your games to friends: Xbox One is designed so game publishers can enable you to give your disc-based games to your friends. There are no fees charged as part of these transfers. There are two requirements: you can only give them to people who have been on your friends list for at least 30 days and each game can only be given once.
Notice they specify disc-based games rather than all games and levy two requirements - games can only be given away once and it is only to people who have been your "friend" for a while. Basically, this is to prevent private sales (i.e. you sell it to me and then "give" me your copy online).
Also, it is publisher dependant - although Microsoft specifies for games they publish:
In our role as a game publisher, Microsoft Studios will enable you to give your games to friends or trade in your Xbox One games at participating retailers. Third party publishers may opt in or out of supporting game resale and may set up business terms or transfer fees with retailers.
So basically, a game may only be "given away" once, to a restricted number of people, and it must be approved by the publisher.
Sharing is where it gets more difficult. They state that anyone can play the game on your console. Pretty much the same as PS+ or XBox live digital games right now (e.g. my wife can play all of my digital games under her PS account as long as she is using my machine). Then they have their special "family access". We don't have details to that other than it will allow your entire family to have access to your library.