It's been going on for a few years. If you look at the level of performance improvements (intel chips have single to barely double digit percentage gains in performance per generation upgrade now, whereas they used to almost double in speed every two years) and at the installed base (good enough screens with good enough resolution, good enough SSDs or HDs with enough space) it just shows that the replacement rate obviously will go down. Back a few years ago you HAD to upgrade to keep up with innovation (audio files won't fit on a 40MB HDD, videos won't fit on a 1GB HDD, HD won't fit on a 32GB HDD etc, XP won't run on 512MB RAM, video compression/decompression will be better on a Pentium II than a 486 etc etc), but honestly what's the difference (to a non-developer casual end user) between say a gen 2 Core i Chip with 4GB of RAM and a 256GB HDD on a 14" 1400 px Screen compared to say a Haswell i5 8GB RAM, 256GB SSD, 15" 1920 px Screen machine. Nothing.
Tablets are facing similar issues. What'll be the big difference between an iPad Air and this year's iPad Air 2?
No doubt. Still using a 7 year old Core 2 <something> Thinkpad and it still works great. Resolution and speed are not a problem. Replaced the hard drive for a solid state, the fan at some point but otherwise I just don't see a good reason to spend another $1k or $2k on a new laptop.
I just bought a Lenovo x220 which is about 2 years old, and it runs both Win7 and Linux Mint perfectly. Very fast, and I can even do SOME gaming with it. Best 200 USD purchase ever. There's no clear reason to upgrade laptops every year, until then I was using a 5 years old HP PC, which was working fine, too.
Shutting down your PC line in Europe is stupid, though. Well, that's better for the other competitors, which will fill the gap.
Tablets are facing similar issues. What'll be the big difference between an iPad Air and this year's iPad Air 2?