According to IC Insights, 89% of the new cellphones sold worldwide in 2015 are forecast to be replacements or additional cellphones sold to existing subscribers. Moreover, this percentage is forecast to rise to 91% in 2016 and to 94% in 2019, which means that only about 6% of 2019 handset sales are expected to be to new customers. This very high replacement sales rate is similar to the situation that already exists in the US automotive industry.

In the future, it will become increasingly critical for cellphone suppliers to convince the existing subscriber base that it needs, and is worth paying a premium for, the newest technology (usually a smartphone) or that it needs more than one handset. If in the future a large portion of existing cellular users become "satisfied" with their cellphones (as happened in 2002 and 2009), it would serve to lengthen the replacement period and have the potential to significantly decrease annual cellphone unit shipment growth rates, IC Insights said.

The vast majority of existing cellphone subscribers upgrade their phones to some version of a smartphone. Smartphones accounted for over 50% of total quarterly cellphone shipments for the first time ever in the first quarter of 2013 and are forecast to reach 410 million units in fourth-quarter 2015 and represent 80% of total cellphones shipped that quarter. On an annual basis, smartphones first surpassed the 50% penetration level in 2013 (54%) and are forecast to represent 95% of total cellphone shipments in 2019, IC Insights indicated.

In contrast to smartphones, total cellphone handset shipments are forecast to decline by 1% in 2015 and grow by only 2% in 2016, IC Insights noted. Non-smartphone cellphone sales dropped by 24% in 2014 and are expected to drop by another 30% in 2015. Moreover, IC Insights forecasts that the 2016 non-smartphone cellphone unit shipment decline will be similar to 2015's drop with a decline of 28%.

Samsung and Apple dominated the smartphone market in 2014 and are expected to do so again in 2015. In total, these two companies shipped 504 million smartphones and held a combined 40% share of smartphone shipments in 2014, IC Insights said. However, although these two companies are forecast to ship 560 million smartphones in 2015, their combined smartphone unit market share is expected to drop one percentage point to 39%.

Samsung's total cellphone unit shipments are forecast to drop by 1% in 2015. Moreover, its 2015 smartphone shipments are expected to grow by only 5%, a weak showing in a market that is forecast to grow 13% in 2015. With a surge in orders for Apple's new iPhone 6s, Apple's smartphone shipments are expected to jump by 20% in 2015, much better than the total 13% growth rate for the worldwide smartphone market. It appears that Samsung is losing smartphone market share to the up-and-coming China-based producers like Huawei and Xiaomi while Apple continues to dominate the high-end smartphone segment, IC Insights suggested.

In contrast to the forecast double-digit declines in smartphone sales of Microsoft/Nokia and Sony in 2015, smartphone sales from most of the top China-based suppliers are expected to surge, IC Insights said. Combined, the seven top-12 smartphone suppliers that are based in China are forecast to ship 437 million smartphones in 2015, a 23% increase from the 355 million smartphones these seven companies shipped in 2014. As a result, the top-7 China-based smartphone suppliers together are expected to hold a 31% share of the worldwide smartphone market in 2015, up 3pp from the 28% share these companies held in 2014 and 9pp better than the 22% combined share these companies held in 2013, IC Insights said.