The tablet market has long been expected to decline, but now it seems as if it has officially hit a wall.

2014 is set to be the first full year in which there is a decline in iPad sales, with no bounce back expected in the holiday season.

Total sales are expected to be down 12 percent from last year, however the bleak expectations go beyond this year alone. A report by IDC predicts iPad sales in 2018 will be 70 million, marginally higher than the 65 million expected to have sold this year.

Not only that, but the tablet market in general is also expected to have a growth rate of around 5.4 percent between 2014 and 2018. Android tablets will also be affected by the slowdown, and expected to show a compound growth rate of around 6 percent per year.

Microsoft, however, is likely to see a rather large increase in the sales of its tablets, which are expected to triple by 2018 to just over 30 million. This figure will still put Microsoft in third place.

The slow in tablet sales growth is largely because consumers replace tablets far less often than other mobile computing devices..

"In the early stages of the tablet market, device lifecycles were expected to resemble those of smartphones, with replacement occurring every two to three years," said Ryan Reith, program director at IDC's Worldwide Quarterly Device Trackers. "What has played out instead is that many tablet owners are holding onto their devices for more than 3 years and in some instances more than four years."

Tablet makers are now facing having to convince consumers there are good reasons to buy a tablet instead of a new PC. The PC market in general is still very large, shipping 300 million units every year.

Total PC shipments for 2014 looks to hit 306.7 million units, with both the Western European and Japanese markets performing better than expected in the third quarter. Despite this, the increase is seen as short-term.

"In the best case for PCs, we'd see a significant wave of replacements as users who spent on phones and tablets in recent years decide they really need to update their PC," said Loren Loverde, vice president of Worldwide PC Trackers at IDC.

"As younger generations become more mobile and Web oriented," Loverde said, "and emerging regions in particular prioritize converged devices (or economy in number of devices to purchase), the PC market will continue to face tough competition and be more focused on replacements, with limited potential for growth."