I would never dream of wanting to ever watch video on anything less than a 14" screen.

I used to take buses every day. I would read to pass the time.

I keep telling my wife that, but she won't listen.

I own only a laptop. A three-year old laptop. It does everything I want from a computer.

Ok, to elaborate.

On a home user level, laptops could probably replace desktops for the most part on a day to day basis. But having a laptop is essentially having all your eggs in one basket and a nightmare to support.

The hardware replacements/upgrades you can do for a laptop are for the most part limited to RAM, HD, and battery. But anything else breaks hardware wise on a laptop, unless it's under warranty usually means you need to get a new laptop.

On a business/office level, having laptops as your primary computer source is possibly the worst thing that business/office could do, unless they love just throwing money and time away.

(Please spare the requested citations on what I'm about to say next since I'm speaking from experience in the IT field as opposed to from a textbook)
The average longevity of a laptop is at best 3-5 years. A desktop's is much higher.

Personally, I feel it very necessary to have multiple computers. I will even use multiple computers at the same time in many cases. But I know I'm not the average computer user, and many would be fine with just one.
I do however think as time goes on, it will be common for your average computer to need more that a single computer, and more than a single type of computer.
The company that finds the best way to easily sync those multiple computers reliably will come out ahead of everyone else.
Google's a great candidate for this type of work because they are well known as a multi-platform friendly company. For instance, they have their own OS on a mobile phone but still offer the same apps on other phones. Google apps work on virtually all popular platforms.

Smaller isn't necessarily better. I myself don't like laptops because the screens are too small, the keyboards are too small and track-pads are way too small and fiddly for me to be able to use with any accuracy. Sure, I could plug in an extra keyboard, mouse and monitor, but then I just have an under-powered desktop machine.

I rather like my new laptop. Spent a whole $940 cad on it, and its a dual core Core2 @ 2.53GHz, w/2G ram (w/room for 2G more), a 15.1" WXGA+ LED backlit screen, and a 9 cell battery that gives me 5 hours or more of uptime, even when the power is out \o/

Now I could have spent about as much on a new quadcore desktop, but I already have 3 quad core desktop class machines, what I really wanted was a portable machine I could move around easily (yay for redundancy), and one that I could work at even on the couch, or in my room, or heck, ON MY DECK (yay for rhyming).