I was intrigued to read the following comment on The Bookseller's Facebook page today: "Something has to be done to save the book in paper format. Not keen on the kindle idea but it's like an unstoppable train. Everything will be digital one day unfortunately but I hope not in my lifetime."

The sentiment that struck a chord was the notion that "everything will be digital one day". It reminded me of the line I've heard at many digital conferences: that even after ten years of digital transformation, still only 50% of music sales come via downloads. In fact, according to Strategy Analytics,  it is not until this year that US consumers will spend for the first time more on online music than CDs (11 years after the first ever iPod was marketed, incidentally).

It is a remarkable statistic, and one which we should remember when thinking about the 12 months ahead. Already in the UK we are seeing strong evidence of the impact on book sales of the numbers of e-readers sold over Christmas, with print fiction books showing a marked decline in sales, as digital adoptees load up their devices with the best new books available. One publisher has told us that e-book sales for one of its titles have made up 90% of total sales in January.

We will no doubt see report after report in the next few weeks indicating that e-book revenue has grown beyond all projection, leading to all too predictable headlines in the wider media as journalists wake up to the news that some people do prefer e-books. Amazon will doubtless add to this fervour when it reports its holiday numbers in early February.

But hold on to your hats. It is very likely that we are simply enjoying the same pattern of growth seen in the US over the past 18 months, with strong e-books sales during the first half of the year and into the summer, leading to a levelling out towards the end of the year.

The most recent numbers published by the Association of American Publishers, for example, showed that October e-book sales were at their lowest since April, and are now hovering at around the 20% mark.

Christmas was also more mixed than you might imagine. While there has been talk of a 'Kindle Christmas', the reports that I've seen from book markets around the world indicate that there was also a general flight to print in the final weeks of the year as gift-buyers looked to physical books to fill stockings and place under Christmas trees.

This is not to underestimate the number of reading devices sold, or the number that will be sold in the 12-months ahead and how this will change everything that we do. But as the digital book market matures we are slowly beginning to see patterns developing and while they are all pointing in the same direction they do not all travel the same route.

[Mike Shatzkin has pointed out the fallibility in comparing the adoption of digital music downloads with that of e-books in an email to me:

Even when you are consuming your music digitally (on an iPod, etc.), you are free to buy it shrink-wrapped, if you prefer, and then "rip" it. When you do that, you get the additional metadata (the little book they put inside the jewel case) and you get something you can then gift to somebody else.

So purchasing can be 50% digital even if consumption is considerably more than 50% digital.

Not true of books. And that's why the analogy is something less than totally helpful as an indicator of what we can expect.

That said: there is evidence surfacing that the ebook switchover is slowing down over here. But I think that's a different story.]