Thats total bollocks (no personal offense meant). There is no evidence that all the 20-somethings arent avid book readers.
And not everyone needs to be an avid book reader, normal amount of being reader is totally okay.
Additionally many have changed over to Audiobooks becasue many only find time in their busy time shedules between making the dishes and driving to/from work.
But most of all its a rennaissance for book reading because never in history have had more people access to, the abillity to and actually bought as many books as they do now may they be on paper, electronic or audio.