I expected PCs to be in every home pretty much forever. Now a lot of non-tech people prefer phones and tablets.
I believe the situation is even better. Desktops and laptops, no longer needing to support the layman on their phones and tablets, will actually become more oriented toward the needs of power users, although their total userbase may decrease. In a decade, Macs will no longer be heading toward being "Facebook machines" because you can do that on your phone, so Apple will focus more on the target userbase of creative digital artists. Windows machines will always need to support word processors and CAD programs but in ways that are cleaner to install and manage. Linux will keep growing to keep up with the number of programmers in the world, so more professional and amatuer solutions will be made available.
There are too many cheap, low quality PC hardware solutions in the market now. Their users will switch to phones and tablets. Higher class hardware will remain the same as the power users will keep buying these.
Also, phones and tablets will remain to be as expensive or more than the future "working man" desktop computer, so this isn't a matter of one wealth class vs. another.
they are not the same thing
they do less; the software is restricted, especially on iOS, there are _rules_ set out by the manufacturer about what is acceptable in software on the platform, both thematically and functionally. An app generally can't interfere with other apps, it can't be a dope wars style game about drugs; there are a lot more caveats, but I am far from aware of them all. For a long time you couldn't get a compiler or interpreter on iOS, so you couldn't use your "computer" to make more software... so it wasn't general-purpose at all, since you by definition couldn't change its purpose without the ability to make new software.
Phones and tablets are great for consuming certain types of content, and having a portable camera with networking has enabled a lot of content creation. But a phone isn't a great device for doing something like long-form writing.
But iOS is not a phone. Windows could set rules about what was acceptable on the platform, but that wouldn't change what a personal computer was. There are no rules about what's acceptable on an iPhone.
so iOS essentially is the phone, since there are no iPhones without it. It's not like you can just pop in an SD card with Linux on it...
Hopefully now that the non-tech people are moving away from traditional PC/laptop, this trend of dumbing down for the "average user" (read: lowest common denominator) can be stopped.