Tuesday night’s return of “American Idol” was down 4 million viewers from last year, according to preliminary Nielsens. The estimate is 33.2 million viewers, down from 37.4 million for its season premiere in 2007. I’m wondering if this is the beginning of a trend — not necessarily of the demise of “Idol,” because 33 million is still a whopping number, but of television. The writers are on strike, there are fewer new episodes of anything to watch, replacement programming sometimes sucks, and people are scouting around for something else to do. Look for reading, bowling and board games to make comebacks?