I'm not concerned about a decline in 'intelligence' among the youngest generations, mainly because I don't think there is one, and mainly because a good deal of what is thought to be intelligence by the general public is nothing of the sort.
What concerns me, and what I do believe we are seeing, is a decline in curiosity--more specificically a decline in the desire to look beyond the walls of one's own life.
And it can hardly be a surprise when the rest of society is going in the same direction.
Geography is the shocker for me--although history is pretty bad: a decline in interest about the particulars of the planet we live on? And the lives of every person who lived before now?
I agree, curiosity matters, the pleasure of finding something out for it's own sake, rather than a point-in-time need, which is served (for many) by the google strapped to your psyche. A 'young' on my recent academic humanties foray said to me; "How do you know so much stuff?"
But there really could be a problem coming and here's why:
It is axiomatic that IQ is pretty heavily influenced by your parents' so a decline in IQ is unlikely. However, intelligence (i.e IQ) is generally considered to separated into fluid intelligence 'Gf', that is, the ability to solve new or novel problems without acquired knowledge and crystallised intelligence 'Gc', is the ability to solve problems based on already acquired knowledge.
As one ages, the former declines and the latter increases, so one's IQ remains fairly constant until some kind of age related cognitive decline sets in.
Gf starts to decline quite early in life as it happens. It can happen at 35, but you or no-one else might notice as you've learnt so much stuff. Most academic's best works come before they are 35, there's a reason for that.
If we have a generation of people who don't care to learn stuff at all, their compensation for declining Gf, the Gc us oldies
had to learn, will not be there, so we're storing up a great wadge of people who will become steadily dumber as they age...which is going to be tricky for them at the very least.
This also undermines the notion that 'rote learning' is bad, because without stored knowledge we're all heading for stupid.
For those of you (oldies) that knew this, you probably also know that exercise and 'using it' are the two best defences. It's also why I keep a notebook - not because I ever look at them per se - but I know that if I read/listen to something, take stock every now and then and write down what I just covered, three to four times more information stays in my head. I could be watching "Bromans" instead though...
(....and now you know why reality TV is bad for us)