Apple may see its first year-on-year sales decline for iPhone shipments this holiday season, a respected analyst predicts.

The company is estimated to sell between 70 million to 75 million iPhone 6s and 6s Plus devices during the holiday sales quarter, compared to the 74.5 million sold in the comparable period last year.

The analyst, Ming-Chi Kuo of KGI Securities, also predicted sales of just 3.5 million to 4 million Apple Watches during the busy first quarter of the 2016 fiscal year, which includes the holiday shopping season, indicating that the wearable has not yet received the mass market interest some had anticipated.

Kuo noted that iPhone sales were strong in the current quarter, which included the launch of the new handsets, but attributed the higher year-on-year sales to increased output of the new phones along with the introduction of China as a launch market aside from the usual territories. He remarked that the current increases were not based on demand.

"As we do not expect overall demand for iPhone 6s to be significantly stronger than that for iPhone 6, we expect shipments momentum could gradually decline in 4Q15-1Q16F on a YoY basis. We expect iPhone may see its first YoY shipments decline in the first quarter of a year in 2016, " Kuo wrote in a research note.

Kuo also indicated that sales of Macs and iPads should remain steady compared with those of the same period last year, with approximately 5.5 million Macs and 15 million iPads expected to be sold in fiscal Q1 2016.

However, Kuo predicted a potential rise in revenues from iPad sales, as he noted that the recently introduced and more expensive iPad Pro will earn the company more iPad sales than its predecessors, including the lower priced iPad Mini.

Kuo also revised his predictions for iPad Pro shipments significantly downward due to supply constraints based on quality issues with the Sharp manufactured panel featured on the slate. Previous estimates of 4 million to 5 million were lowered to 2 million.