I think one of the more long-term threats to Qualcomm is the relative decline in importance of gen on gen improvements in mobile networking and smartphone AP performance.
3G to 4G was a massive change. It made many application on smartphones actually viable. While we don't have 5G where I live, I get the impression that it's not that big of a jump. I have yet to see any mass market application that require 5G.
Same with smartphone CPU performance, while there is still a lot of room for further developments (particularly in efficiency/battery life), modern smartphones are a mature product category. Most smartphones users do not need a top of the line smartphone CPU. Not to mention replacement cycle lengths are trending upwards, 3+ year upgrade cycles are becoming much more common.
I am skeptical about Windows on Arm, we have yet to see any substantive real world benefits (i.e. not just benchmarks) for Snapdragon Elite X laptops. It's basically the same thing as buying a modern x86 laptop, but with more problems.