Much of the transition has already happened - most applications have already moved on from C to safer languages. What's coming is either the replacement of C libraries (Rust, very careful C rewrites), or perhaps bypassing them entirely (OCaml unikernel work).
I would fear more for proprietary systems. Open source is relatively innovative and adaptable.
We are kind of crowning the right to rule of the x86 computer industry. llvm is very tied to apple, maybe it can extend to ARM. But it means that some HW platform that may be to old may be difficult to maintain in the future (HPPA, Dec alpha, MIPS, PDP, zseries?).
And some computers have life cycle that are more than 10 years. (Expensive industry robots, telco switches, some medical devices, aeronautic/space CPU, radars, some very old mainframe used for accounting, embedded automation devices)...
Is this push to obsolescence really cool?
Okay critical system already handle the problem, but what about the stuff in the grey zone? Stuff that were not critical but get adopted nonetheless because they just worked and good be updated?
Huh? Higher-level languages are much more portable than C - you only have to port the language runtime, and often someone's done that already. LLVM has a lot of different backends available.
hum.... well. If you imagine that they are 100% idempotent on every platform and 100% fully supported. It would work.
But as I stated in my example python/Perl/C# and probably others are in the language support dropping either some platform or supporting only x% of the feature on some platform...
I dare you to access you services using C#/mono on openBSD.
I'm running FreeBSD as it happens and C# works absolutely fine - I have even just downloaded random .net exes and run them and had them work.
If you had a race where you picked a random C program and a random python/perl/C# program off github/sourceforge/whatever and tried to run them on OpenBSD, I'm pretty sure 9/10 times the python/perl/C# would win.
Remember 90% of programming is internal tools for businesses, not consumer applications.
(Also in a lot of cases you wouldn't necessarily notice. If you've played a few recent games you've likely run at least one written in C#. I've seen commercial drivers written in Python that you only notice if you look in the internals)
I would fear more for proprietary systems. Open source is relatively innovative and adaptable.