The primary concern for a smartphone, in my opinion, is its battery longevity, an area where Samsung devices have not consistently excelled. To enhance customer satisfaction, particularly for users like myself, it would be beneficial if Samsung considered incorporating silicon-carbon batteries. For instance, a 7500 mAh battery could be readily integrated into the S26 Ultra model. Should battery life improvements not be prioritized, I may consider switching from Samsung to other brands, such as the Oppo Find X9 Pro.
Another significant aspect, which Apple has addressed with its 17 series, is Pulse Width Modulation (PWM) for eye protection. It would be highly advantageous if Samsung implemented PWM in its S26 series, with the S26 Ultra potentially featuring a PWM frequency of 2000 Hz or higher.
These two factors are crucial for Samsung's success in sales. Additionally, a minor but noteworthy improvement would be the inclusion of Bluetooth 6.0 instead of 5.4.
While the features you mention are certainly desirable for many users, it is a bit of an overstatement to suggest they are currently crucial for success in sales. Both the S25U and iP17ProMax feature ~5,000mah Li/ion batteries and far, far exceed the US sales of the Chinese phones you mention.
