Gartner is forecasting tablet computer sales of 19.5 million units in 2010, mainly due to the popularity of Apple's iPad.
The upward trend appears set to continue for at least the next four years, as tablets replace other devices such as e-readers, gaming handsets and media players.
In its latest report on mobile devices, Gartner predicts tablet sales of 54.8 million units in 2011, 103 million in 2012, 154 million in 2013, and more than 208 million in 2014.
"Mini notebooks will suffer from the strongest cannibalisation threat as media tablet average selling prices drop below $300 over the next two years," said Carolina Milanesi, researcher at Gartner.
Low-end consumer notebooks will suffer only marginally from cannibalisation, but Gartner expects the biggest impact will be on high-end smartphones.
"It will be hard for a user to justify owning both when the differentiation in usage model is very limited," said Milanesi.
Users buying a 7-inch tablet might opt for a lower priced smartphone with a smaller form factor, she said.
But for the enterprise, Gartner predicts 10-inch tablets will be used alongside notebooks for the immediate future or as a secondary device to take on the road or use for fast access to e-mail, calendaring and web apps, and for showing presentations.