I do not see what the big deal is. Is the internet required to play a single player game? If so, I can an issue... If it is required only to activate the game, then PC gamers are all-to-familiar with this. Not to say this will happen, but if MS is planning on locking out the used game market, there should be a $10 drop on the price of new releases to reflect prices in the PC market. Yes, part of the reason for the lower price on PC games is the lack of royalties paid to produce it, but that is more than made up for in volume on console games. I can see new game prices undercutting PS4.
Second, let us keep in mind that most of the features Microsoft showed off were of the media-centric variety. For many of these things, complaining about requiring an internet connection is like complaining that your internet browser doesn't work right without the internet, or that Netflix Instant doesn't work when the internet is out. Downloading TV guide information, showing your fantasy team, those kinds of things require the internet. Everything I have seen so far suggests that for the BEST experience with the Xbox One, you need an always-on internet connection. Ok.
Now, I could be wrong on all of this, but my gut says that, at most, if Microsoft wants to lock out the used market, they will require internet to "activate" your game, which is a pain I am sure in rural areas, but I was a doubter of this whole "Steam powered web game machine", but I honestly cannot imagine being tethered to a disc anymore.