I'm not convinced boredom was normal per se - people find stuff to do. It's just that the nature of stuff has changed, as has the availability. 20 years ago it was browsing the internet for hours. Before that it was watching TV. Before that there was Other Stuff, like going exploring with a friend (for me). But the 2000s changed things, people got mp3 players and an infinite library of music, smartphones and an infinite amount of activities to do on them at any point of day, internet on the go instead of going to The Space With The Computer, streaming / binging programs instead of having a fixed moment in the day, looking up what's on tonight in the TV guide, or renting a film as a weekend activity.

It's all more instant and always available. I mean books were too (at some point people were complaining about kids these days always reading), but it's different.

Am I worried? A little, because at the same time I keep reminding myself that every generation was worried about what people are up to this time. In 20 years people will probably be nostalgic for today in some way.

You're very right, back in the day a lot of people would complain about people reading newspapers on trains/buses and why these people "just can't let their mind wander" or whatever the argument was. Today you'll instead see people telling others they should put down their phone and read something "physical" instead, I don't think a single person today would complain about others reading books/newspapers on public transport.

In the future some people will surely feel the same about "Device X" and smartphones, and ask themselves "Why can't they be old school and just sit with their smartphone instead?"