Research firm IDC forecasts more difficult times ahead for the world’s PC industry with desktop machine sales on the decline through 2020 and portables only increasing slightly.

Says IDC: “Unfortunately, the PC market still faces some persistent challenges, and for now, improvement continues to mean slower declines.”

In an updated sales forecast issued Thursday, IDC expects sales to fall more than 7 percent this year to just over 103 million.

While that 2016 decline is better than what IDC says is an “unprecedented” double-digit decline over the past four quarters, it’s still two percentage points worse that predicted earlier.

Shipments fell overall by 12.5 percent.

Looking ahead, IDC sees shipments declining to 249.5 million in 2020 from 255.6 million this year.

The industry faces a variety of challenges, such as more consumers and businesses shifting to smartphones and tablets. Other factors IDC noted include: “weak currencies, depressed commodity prices, political uncertainty, and delayed projects.”

But sales in phones and tablets have fallen, too. In another bad sign for PC makers, those declines haven’t meant more PC buyers. Tablet sales are not counted in IDC’s shipments.

“Although growth rates for devices such as phones and tablets continue to fall, potentially reducing the competitive pressure on PCs, we have not seen this translate into stronger PC shipments,” Gartner noted.

Not even so-called “detachable PCs,” such as Lenovo’s Yoga on which the world’s top PC maker has invested heavily, offers much hope for manufacturers.

“Detachable Tablets also present a growing challenge as specs and price increasingly compare favorably against notebook PCs,” IDC noted. “Combining detachable tablets with PCs, the market is projected to decline by just over 2 percent in 2016 with small positive growth in later years, though still falling well short of peak shipments.”

IDC does forecast slight improvement in notebooks and laptops, rising to 155.3 million from 152.3 million this year.

However, desktop shipments are expected to fall well under 100 million to 94.2 million from 103.3 million this year.

“The latest update reflects continuing pressure on PC shipments, but does not significantly change the factors driving the market,” said Loren Loverde, vice president of Worldwide Tracker Forecasting and PC research at IDC. “In addition, we have now had four consecutive quarters of double-digit volume declines. This type of prolonged slump is unprecedented, and lowers the bar for some improvement going forward. Unfortunately, the PC market still faces some persistent challenges, and for now, improvement continues to mean slower declines.”