It's been a long, hard fall for BlackBerry (NASDAQ:BBRY). In 2009, the company held 55% of the U.S. smartphone market share, and today it holds just 4.8%. In 2007, BlackBerry's share price peaked around $145 and has since dropped more than 93%.

What's scary for tech companies is that they rarely see a fall like this coming. For BlackBerry, Apple's (NASDAQ:AAPL) iPhone helped push the all-consuming Crackberries into irrelevance. If history is any predictor of the future, then one of our current beloved technologies could be on the chopping block in the coming years.

Say it ain't so, iOS
Let's start with a biggie. Apple's revolutionary OS changed the way people interacted with their smartphones and helped foster a consumer culture of touchscreen mobile devices. The success of the iPhone and iPad wouldn't have happened if consumers didn't connect with iOS -- and they did in big ways. The mobile operating system now accounts for 42% of smartphone sales in the U.S. and 48% of worldwide tablet shipments.

Iphone





iPhone 5 with iOS 7. Source: Apple.

But iOS has lost a bit of its luster as of late. Apple just introduced iOS 7, a complete aesthetic overhaul of the OS in attempts to freshen the product. Apple has updated and introduced the OS over the years, but until the forthcoming version was introduced, many of its features seemed largely the same as when it launched in 2007.

Worldwide, iOS is battling with Google's (NASDAQ:GOOGL) Android, which currently holds 75% of worldwide smartphone market share and 43% of tablet market share by shipments.

It's seems hard to imagine iOS as not being a dominant mobile platform, and according to IDC it will remain in the top two spot for the next five years. But as Samsung and Android continue on their warpath, and mobile users deal with at least some iOS fatigue, it's not out of the realm of imagination for Apple's popular OS to be replaced by something far better.

Et tu, Android?
In 2010, Apple and Android had a combined 23% market share. Now, Kantar has Google's OS at 52%  smartphone market share in the U.S. by sales, but stalling slightly as iOS makes gains. Android is on a roll in Europe as well and making huge gains in developing markets such as India, where it enjoys 90% smartphone market share by shipments.

Galaxy S
Galaxy S4. Source: Samsung.

Android's growth has been partly due to handset companies' realization that the only way to compete with iOS was to adopt the free OS and flood the market. And it's worked very well. IDC expects Android to stay the dominant smartphone OS until 2016.

But even as Google has created an impressive operating system, the company is aware that handset makers could take what they've learned from Android and create their own OS. Samsung has customized Android more than any other OEM, and its consumers have responded. While Samsung relies on Android for its mobile OS right now, it's also working on it's own operating system, called Tizen. Samsung easily ships more Android phones than any other handset maker, and if it ever switched to its own OS, it could disrupt Android's dominance in a lot of markets.

Samsung is already creating a high-end Tizen phone, with a release date set in August or September. Any change away from Android would surely be a slow and cautious one, but it does show that Samsung -- a company that's profited greatly from Android -- is willing to step out and try something different. And trying something new is the first step in disrupting a current leader.

The untouchable iPad
I know, I know, it's the iPad, for goodness' sake. But trust me; it's still vulnerable. Apple's device is the dominant tablet right now -- taking up almost 40% of worldwide tablet shipment market share in the first quarter of 2013. But new tech like flexible displays and wearable computing could make it less relevant in the future.

Google Glass and smartwatches have the potential to disrupt current mobile offerings in ways that are hard to imagine right now. Flexible displays have the potential to bring screens into places they never existed before and offer a completely different user experience. Some are even talking about internal wearable technology that gathers data on the go and transmits it when and where it's needed.

Ipad
iPad. Source: Apple.

It may be that another company simply comes out with a better tablet, one with much more functionality than the iPad. Perhaps a flexible tablet will take its place, or a new era of wearables could make the iPad seem archaic. Skeptics who think the iPad will remain on top need to look no further than Sony's Walkman. The company dominated mobile listening devices for years before Apple swooped in with the iPod and proved that no device or brand can stay on top forever.

Pondering the future
While we don't know which devices or systems will disrupt the current ones, we can be pretty sure that it will happen. That's why it's important for investors to keep up on new technologies and try to see how they could fit in or displace current products. Tech companies spend millions developing new products, and not all of them make it to market, but keeping an eye on what's coming down the pipeline and who's doing the most innovating is an investor's due diligence.

Fool contributor Chris Neiger has no position in any stocks mentioned. The Motley Fool recommends and owns shares of Apple and Google. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.