It is unquestionable that multiplayer dominates in most games that support it, over their single player campaigns. Games like World of Warcraft and Warhawk (PS3) are almost exclusively programmed for online gaming, and they have proved to be very successful till now and there is no signs of slowing down, as add-ons for WoW keep coming and keep selling very well. BUT i cannot agree with this article, as not everyone in the world has a DSL cable hooked up to their console.
Nor a speedy DSL for that matter. If the console is geared towards too much online dependency, it will only sell in specific regions of the world, like in developed countries mostly, which have easy and cheaper access to high speed internet.
Also, no one wants to have to wait hours for a game to download before they can finally play. Pioneer has made a 400GB bluray disc and it is obvious that the bluray has a LOT yet to deliver. Games are undoubtedly going to get bigger as the quality rises.
Downloading a 400GB game isn't going to be a big selling point. Most of us would rather just buy it and pop it in the drive of the console and just play away. Also, what would happen if you need hard disc space for other games/media? Delete the games you bought and downloaded? Having them on disc already saves all this trouble.