The latest tablet data from research firm IDC has gone from bad to worse.

In February, IDC reported a 3.2 percent drop in Q4 2014 tablet shipments, marking the industry's first ever year-over-year decline. But at the time, the research firm left a sliver of optimism that the market could still grow if all of its moving parts lined up correctly.

The latest outlook, however, is a bit grimmer. IDC has scaled back its five-year forecast for the tablet category, now predicting tablet shipments to reach 234 million units in 2015, a modest annual increase of 2.1 percent over 2014.

While bleak reports about a stagnant tablet industry are hardly shocking these days, IDC does provide an interesting perspective on the vendor dance that is taking place on the tablet seller leader board.

According to IDC, Apple's lead in the tablet market has officially slipped through its fingers. IDC called Apple's flagship tablet and operating system the "weakest link," with analysts predicting Apple's volume share of the market to reach levels below that of the past three years.

As for current shipment leader Android, the outlook is also less than promising. IDC says it expects Android shipment volumes to grow slightly, from 154.7 million in 2014 to 158.1 million in 2015. But jump to 2019 and the predictions are dismal, with Android's market share dropping to 62.9 percent.

The only tablet maker whose dreams are not totally squashed by the report is Windows. Despite modest adoption to date, IDC expects Windows tablets to gain significant share over the next four years, growing from 5.1 percent in 2014 to 14.1 percent in 2019.

"Microsoft is doing a lot of good things right now and we believe the launch of Windows 10 later this year will not only have a significant impact on Microsoft's share of the market, but on the industry as a whole," said Jean Philippe Bouchard, IDC research director on tablets.