First-quarter 2017 results of Taiwan-based makers in the iPad supply chain, notably touch panel makers TPK Holding and General Interface Solution (GIS), are hanging in the balance, depending on when Apple is going release its new iPad Pro lineup, according to industry sources.

Upstream suppliers said earlier that Apple is planning three new tablets for 2017, an entry-level 9.7-inch iPad, a 10.5-inch iPad, and an upgraded 12.9-inch iPad Pro.

Recent market situations - including frequent out-of-stock notices for 12.9-inch iPad Pro and 9.7-inch iPad Air 2 on Apple's online store; reduced pricing for 9.7-inch iPad devices in Asia - may serve as indications that Apple is likely to release new iPad soon, said the sources.

Vendors have hoped that at least one of the two large-size tablets, 10.5-inch iPad or the 12.9-inch iPad Pro, will be released in the first quarter of 2017 along with the entry-level 9.7-inch iPad.

However, the sources said that they are now more certain that both of the planned two large-size models will not come until May-June, thereby affecting first-quarter sales of supply chain makers.

TPK is expected to see its revenues drop within a range of 10% sequentially in the first quarter of 2017. But the company is still likely to post growth for the first half of the year thanks to follow-up orders for the new iPad Pro lineup, commented the sources.

GIS, a subsidiary of Foxconn Electronics, is expected to see its revenue decline over 35% on quarter in the first quarter, from the NT$29.623 billion (US$963.28 million) of a quarter earlier, the sources estimated.

However, orders from Apple as well as non-Apple handset, tablet and notebook clients will help GIS boost sales for the second quarter and eventually for the first half of the year, said the sources.

Overall, shipments of iPad devices are expected to reach 40 million units in 2017, down slightly from a year earlier, the sources estimated.