I can't comment specifically on the Linux kernel piece, but I want to point out, broadly, that security has generally been an afterthought, and very little gets invested into it in terms of time and money - as a general rule.
Multiply that behavior times the number of commercial and mobile and b2b apps over 50+ years, and that's where we are.
There will likely be many more leaks, and hacks, and outages. And then in trying to be proactive to fix old systems, that will cause new proactive outages, and then eventually many things will be better.
But, it's going to take a lot of time and investment, and a lot of (majority) of currently unsupported devices will have to be complete replaced / scrapped / ewaste. On the scale of Nation-State initiatives.
This is across all operating systems, firmware, software and devices of all kinds, etc.
LLMs to security are like a bomb went off. We still have to wait for things to fall over before the dust will even clear enough to see what we have to work with.