A few technology trends have come down to a reasonable price point and a consumer-grade experience in terms of not needing to be a technical expert to leverage the service recently.
For instance, this post is being done from a plane on an iPad. Most airlines have experimented with various forms of wi-fi over the years but it is now closer to being widespread, at a good price point (around $10 or so), and now it is not only useful for laptops but for a wide variety of other devices including mobile phones, tablet computers, and of course laptops.
I remember when a phone on an airplane was a game-changing technology, because you weren't totally out of pocket from the time you left the ground until your return. That model is pretty much gone now, but it likely was a decent revenue source for the airlines for some period of time.
With wifi being a source for not only surfing the web, social media, but also messaging (especially through Apple's messenger technology, which uses wi-fi instead of cellular networks and also tells you if you message was "delivered" or not, if you send to another Apple device) and face-time (I don't see people doing that on the plane now, but it is likely coming), the connectedness of it all is much higher than was feasible or practical with prior technologies.
In parallel, the cost of a device that can efficiently read and communicate effectively has plummeted, with iPads declining in price (while adding features) and with many phones nearly free on various plans. While a PC is a cumbersome device with slow start up, anti virus software, and myriad programs, tablets are available immediately and are much quicker to view movies, social media, or play music. The Mac is obviously much closer to a tablet-type experience than a typical PC.
Airlines that invested heavily in in-flight entertainment technologies devoted significant capital spend and also weight that reduces fuel mileage and capacity on every flight. Enabling wifi for the aircraft and having consumers bring their own devices fundamentally changes that equation. Those airlines that avoided the spend and investment and just let patrons bring their own device (which pretty much everyone already has) can leapfrog and avoid the cost, hassles, and ongoing weight of these solutions, while being able to collect for a new revenue stream, wi-fi.
It will be interesting to see if airlines keep charging for wi-fi or if it just becomes "free". Many of the lower-end hotels and motels give away wi-fi, and the high end hotels charge for it by the day. This is likely due to competition at various customer segments and price points - on the low end the people staying at those hotels are limited by price and then they won't select a hotel that doesn't have free wi-fi. On the other hand, the high end hotels are booked for many reasons including location and amenities so perhaps they feel that lack of embedded wi-fi isn't going to deter potential customers.
PC's are on a slower upgrade cycle and much of it is due to competition from devices like iPads. As iPads get more powerful and useful generally people only go to a PC to "do work" and much of the work is email and the like and the iPad or phone is quite capable of that same level of functionality. It almost seems like tedium now to turn on your PC and wait in order to work with it, and it certainly isn't exciting or inspiring me to go out and upgrade to a new PC.
Airports themselves will be different, as well. The newsstand used to be a very busy place as you bought a book or newspaper for the flight - if you have your ipad and wi-fi, however, you don't need paper copies. These bookstores and magazine stands don't seem to be as busy as they used to be.
This photo is from our blog from a Southwest Airlines flight. As someone who has traveled for many years, the ease of communications and the power of these devices (and quickness to start up) is amazing.
One last item is that people were very worried that when cell phones were allowed on planes, that people would annoy the heck out of each other talking the entire flight. Many people nowadays use their mobile devices more for messaging and similar communications, and young people especially are less likely to make a call and engage in a long (and annoying to their seat-mates) conversation. With wi-fi and messaging communications is now mostly silent and the plane is now a library, with everyone glued to their personal devices.