1) Apple will start to lose desktop/laptop market share.
While Apple has never really had a large share of the market, they have been making slow but steady gains the last few years. The biggest increase for Apple is in the college demographic. However, with the stumbling economy, the masses will buy fewer and fewer computers from Apple as they start to do a simple cost/benefit analysis. This will lead to a full reworking of Apple's marketing strategy and long-term plans, thus leading to the new market for Apple.
2) Apple releases a tablet/netbook/large iPod-Touch.
This new market, and new strategy, for Apple will be the release of a netbook/tablet that is essentially a large-screen iPod Touch. While this will get huge sales initially (helping to bump up the netbook market), it will quickly steady out and remain at the roughly 20% market share that Apple currently enjoys. The iNetBook will feature a touch screen, with a stylus as well, and OSX Snow Leopard. Unlike most netbooks, Apple's will be priced in the $500-$600 range, but that should not keep Apple from getting their normal support (I will be buying it the day it comes out).
3) The Netbook market takes off, but Windows XP remains the primary OS.
With the economy going towards the gutter and consumers spending far less than in years past, low-tech gear will gain in leaps and bounds. Most people want computers to e-mail, browse the Internet, and maybe look at pictures, and netbooks fill this niche perfectly. In 2009, netbooks will take about 20%-30% of the laptop market share and will remain in the sub 400$ range. Regardless of any Linux options or any future Apple OS, Windows XP will remain the king of netbook systems.
4) Microsoft will start a phone company, the iPhone will keep growing, Android will stumble.
The Apple iPhone, with its sexy look and easy-to-use touch screen will continue to grow in market share, while its app store makes millions for Apple. The iPhone, which will be available in larger sizes and memory configurations, will soon become the market leader of smart phones. Android, which launched with some fanfare, will soon plummet and disappear as most companies realize that it is better to have a company who can advertise their OS as opposed to you having to do it. Microsoft, in an attempt to keep Windows Mobile alive, will either create a Zune phone or make a play to purchase RIM (BlackBerry) which will give them a strong standing.