I'm not sure the XP/7 situation is a good comparison for 7/10 though. In the former case, the main concern was incompatibilities and the general time and money

I'm not sure the XP/7 situation is a good comparison for 7/10 though. In the former case, the main concern was incompatibilities and the general time and money costs of a large-scale software migration. In the latter case, you have the same issues, but on top of those there are compelling reasons not to move to 10 for some organisations. It's not a case of delaying the move as long as possible to avoid incurring the overheads; they actively don't want to make that move at all. I agree about the importance of backward compatibility for Windows itself, but I think compatibility is becoming less compelling as a reason for businesses to stay with Windows. The dangers of lock-in are well understood and a lot of businesses have been changing their IT strategies accordingly for a long time. For example, in the era of XP to 7 transitions a decade or so ago, Office was the de facto standard format for exchanging most information within and between businesses. Today a wide range of online services are used for communication, and the tools for importing and exporting Office files from other software are now adequate for many purposes, and it's unlikely either of those trends will have reversed by 2020 when 7 runs out of support. As of today, my own businesses have only a couple of Windows-only applications left that we rely on for anything fundamental. They are also the biggest pain points in our whole software infrastructure, also supplied by huge developers that have been moving in customer-hostile directions in recent years, and they are also starting to face serious competition from other applications on other platforms. Whether shifting away from Windows forces us to drop those few remaining Windows-only applications or dropping the applications removes the remaining incentives to stay on Windows first, I fully expect that by 2020 we won't be sorry to see any of them go.