The latest numbers published by the firm project Apple's end of year share will fall to 73.4 percent, down from 83 percent a year earlier.
The reason, of course, isn't that iPad is proving less popular, but rather the market as a whole is expanding.
UI the USP
The total number of consumers purchasing tablets will rise by 261.4 percent across the same period, equating to 63.6 million units worldwide.
That's a far cry from the 17.6 million units sold in 2010.
"We expect Apple to maintain a market share lead throughout our forecast period by commanding more than 50 percent of the market until 2014," said Gartner research veep Carolina Milanesi.
"This is because Apple delivers a superior and unified user experience across its hardware, software and services."
And Android?
In comparison, Gartner estimates Android will bag itself a 17.3 percent share of the tablet market by the end of 2011, equal to 11 million units sold across OEMs.
That's a slight increase year on year, but down on the 28 percent calculated last quarter.
"So far, Android's appeal in the tablet market has been constrained by high prices, weak user interface and limited tablet applications" added Milanesi.
"Google will address the fragmentation of Android across smartphone and tablet form factors within the next Android release, known as Ice Cream Sandwich, which we expect to see in the fourth quarter of 2011.
"Android can count on strong support from key OEMs, has a sizeable developer community, and its smartphones application ecosystem is second only to Apple's."
Any other business
It's RIM's prospects in the market that Gartner assesses most harshly, however. The firm believes less and less developers are willing to commit to working on BlackBerry hardware.
Windows 8 will also suffer in the years to come, so Gartner concludes, due to its lateness to the party.
"Most of Apple's competitors are struggling to meet Apple's prices without considerably sacrificing margins," added principle analyst Roberta Cozza.
"Screen quality and processing power are the two hardware features that vendors cannot afford to compromise on. ]
"They should consider everything else 'nice to have,' rather than essential, in order to keep bills-of-materials costs competitive with those of the iPad."
[source: Gartner]
