The quality of modern literature may well be declining, but the is literally endless reading material everywhere
I think parents have to counteract the negative effects of this by exposing their kids to the joys of words and reading. I agree with you 100% that there's an amazing diversity of texts out there now! Every so often when I grab an ereader I think about how blown away I would have been as a kid to think that I could take HUNDREDS of books with me on vacation.
When I was a kid I had a ton of books from my parents in the house and when bored I could pick one up.
That's not the same as having a computer, tablet or phone, cause kids will gravitate towards non-reading activities.
(If everyone in the family owns an e-reader this obviously would be a different situation)