Apple is likely to see continued weak sales for its iPad product line during 2015, according to a DigiTimes report which cited sources in the component supply chain.

The publication said that even though Apple is set to unveil two new iPads – a refreshed iPad Mini as well as the previously-reported large screen iPad – shipments are still expected to drop due to increased demand for large-size smartphones.

Indeed, it has previously been suggested that the launch of the larger-screen iPhone 6 Plus could end up cannibalising sales of the iPad, although Tim Cook, CEO of the device maker, played-down this concern, arguing that “it is what it is”.

But while the launch of the iPhone 6 Plus seemed most likely to impact the iPad Mini, DigiTimes said that the order is impacting the 9.7-inch iPad Air line in particular.

Certainly part of the issue is likely to be the different replacement cycles between smartphones and tablets. While the former see rapidly advancing feature sets, coupled with operator service contracts and subsidies which drive a fairly regular upgrade rate, tablets in general have seen a more incremental upgrade path.

With no massive step forward in terms of functionality, and without subsidised sales to lure buyers, tablets seem to be having a longer shelf life than smartphones, meaning the upgrade cycle will be more similar to PCs.

With it being only just over five years since the launch of the first iPad, and with a number of new devices having been announced in the interim (iPad 2, iPad 3, iPad 4, iPad Air, iPad Air 2, iPad Mini, iPad Mini 2, iPad Mini 3), the number of still relatively new devices in use is high, leading to a slowed refresh rate.

Through its partnership with IBM, Apple has been looking to drive iPad adoption in the lucrative enterprise market, which is where a large screen version (generally referred to as iPad Pro) would also come into its own.

According to reports this week, such a device would feature a number of new features, including a Bluetooth stylus accessory and improved touch screen, and USB-C connector.