I for one think that that's great. It helps encourage people to upgrade but it also makes things a lot easier to support. It's not friendly to the poor though. If you bought an older all aluminium macbook say in college and due to it being built like a tank you use it for 5+ years and it goes out of support what then if you're not making enough free cash to dole out on a 3k macbook?
I am admittedly pretty solidly middle-class, but I've never had a non-Apple computer last anywhere near 5+ years, so I'd say they were still getting a pretty decent deal relatively speaking.
But in any case Macs and iDevices are different; Macs tend to stay backwards-compatible for quite a while longer. 32-bit apps still work fine and will as long as Macs are on Intel processors. Even Carbon[1] apps still work (compiled as x86 binaries) on the latest MacOS, and those will also run (compiled as PPC binaries) on MacOS 8.1, from 1998.
Next year my mid 2013 MacBook Pro will be 5 years old and the thing still smokes most lesser PC laptops. The battery still has more than 50% of the charging cycles left and it all runs really well. I figure I’d keep it until it died which could be another 5 years.
