Gartner: Still no true iPad challengers through 2015

lots of tabletsMedia tablet sales are set to grow from 17.6 million last year to 326.3 million in 2015, and the bulk of them will continue to be Apple iPads(s aapl). So says Gartner, (s it) which on Thursday put forth a four-year estimate of tablet sales by operating system. The numbers reflect that Apple has a large head start with a mature tablet, as all other competitors are still struggling to catch up. That premise doesn’t surprise, but Gartner’s projected growth of QNX-powered tablets does.

Even over the next four years, as competing tablets and their supporting ecosystems mature, Gartner projects Apple’s iPad will hold a majority share of all tablets sales over the next four years. Android will continue to chase for the No. 2 spot but still manage just over a third of market share by 2015, while QNX(s rimm) and Microsoft(s msft) slates bring up the rear. HP (s hpq) is considered to be out of the game completely due to abandoning the TouchPad hardware business with a massive inventory fire-sale. I think there’s a very slim chance that situation reverses itself due to speculation of HP replacing its current CEO, Leo Apotheker.

Here’s how Gartner sees the tablet market taking shape, with all figures in thousands:

A few thoughts jump to mind. First, I don’t doubt Apple’s dominance in the tablet market throughout the next few years. If anything, I think it’s understated by the estimates. That’s not to say the iPad is the best tablet for everyone, but it currently has the broadest customer appeal and most mature ecosystem for applications and services. Apple gave itself a good 18-month lead in the market and others are still scrambling to offer a fully comparable tablet experience.

I also wonder how Amazon’s(s amzn) upcoming tablet plays into the estimates as we already know the device is based on Android, even if it’s heavily customized so as to hide Google’s interface. The same holds true for the popular and extensible Barnes & Noble Nook Color(s bks), which ought to see a hardware refresh in the near future. I suspect that with weak sales of traditional Android tablets, these combination e-readers / tablets will make up the bulk of Android tablet sales, but Gartner makes no comment on that aspect.

Then there’s QNX. Earlier this week, I noted that Research In Motion (s rimm) shipped a scant 200,000 PlayBook tablets with QNX in the most recent quarter. That figure follows an estimated 500,000 PlayBooks shipped in the quarter prior to that. The data reflects shipped PlayBooks, not actual sales, and even if they were sales, I don’t see how Gartner expects RIM to sell 3 million PlayBooks this year. Even with a software update to add native email and support for Android applications, it appears impossible that RIM will sell 2.3 million tablets or more between now and the end of 2011.

It’s too early to call out any numbers for Microsoft (s msft) tablets, although a touch-friendly Metro interface and ARM (s armh) processor support for Windows 8 gets Microsoft in the game. Gartner expects a reasonably quick uptake once Windows tablets arrive, but I’ll wait and see the final product before taking a stab at sales. Regardless, the iPad is still the once and future king of tablets; at least for the next few years.