The only people I know who dont have computers are my friends working heavily blue collar jobs. Even most of them have laptop's, only a few don't have anything.
Couple years outta college? People are still using the PC they bought for college probably. I don't know a whole ton of people who went to college anyways.
Using a smartphone to do anything other than send short messages and read the web frustrates me to buggery, but for those people who find using a computer frustrating or tedious anyway a smartphone mustn't be much different or even probably a better user experience.
It's all social media/chat apps for them now.
Booking flights is easy, I use Kayak.
Hipmunk?
And those who have, no upgrades, but shining new cell phones and tablets.
That's not how it works.
It's not "obviously" declining because of smartphones and tablets, at least not to me. Pretty much everyone has a computer (in the US), as it doesn't make sense to do many things on your cellphone (like write emails). They just aren't upgrading because they don't need to.