That the web trains users not to sustain their attention seems obvious, since hypertext was famously designed by
someone with ADD. But isn't the solution to mental skittishness to exercise your abilities by reading lengthy and/or challenging texts offline? How useful is it to shake your fist at the internet? If I have the tendency to eat laminated birdfat-infused Sugar Boulders™ because they're too easy to find in my local gas station, then should I burn down the gas station or spend more time in the produce sections of supermarkets?
As for videogames, I'm still waiting for them to develop into the non-stochastic art form that Robert Ebert said was impossible: A medium that effectively synthesizes movies, books and music, and can offer sandbox narratives that are completely player-determined down to style and visual details. Hypertext novels hinted at the possibility, but novelistic/cinematic games took the stochastic multimedia novel a lot further (
cf. Fahrenheit, Ico, Hotel Dusk, Heavy Rain, Nocturne, Silent Hill 2 and Rule of Rose -- and that's only counting the Zeds).