I sat on the train, on one of my twice-a-week visits to London, and couldn't figure out for the life of me what was different about the table of four diametrically opposite me. It was only when someone popped their book down on the desk, and closed their eyes to nap for a while (it was a pretty early train), that I finally twigged. Every single one of them in that foursome was reading a paper product of some kind: a book, a magazine, a newspaper.

It had been at least a year since I'd last seen that. These long distance commuter trains have become the preserve of the electronic device. People reading books on their Kindles – by far the most common device right now. People playing games, or watching TV shows, or catching up on their e-mail on their iPads. Idly texting on their phones as a distraction.

In the week that Amazon announced that the Kindle would be coming to Europe – the UK included – perhaps I should have noticed more quickly. But somewhere over the past 18 months, the sight of an ereader of some description – the Sony and Kobo models are in evidence as well – has gone from being a rare thing to ubiquitous.

A couple I was sat together on the train back this evening, the bloke happily gaming on what looked like and envy-inducing new iPad, his girlfriend wrapped up in a book on her Kindle, summed up the new reality of commuting. My wife is perhaps the only regular reader who still holds out against the advance of the eBook, preferring to pick up cheap paperbacks in charity shops. For the rest of the commuting populace, bits are king.

Paper has become remarkable, digital unremarkable. That's pretty post-digital.

I can't help wondering what comes next, though. For all the ubiquity of the digital book platforms, they're still just carrying, well, books. They're not manifestly different from what was being carried by paper. I wonder where the real innovations will be for those word-hungry commuters, and where they'll come from…

Robin Sloan's Fish is the most interesting experiment with the digital writing form I've seen in a while, but that's built for smartphones. Surely some experimentation with the eBook form is called for?