1. C language toolchain -- No specifics (save static analyzers, ... because C needs static analyzers to catch C specific bugs...). What do you actually feel you're missing? Most of these "new C" languages use the same backend as a C compiler. What can't you use?
2., 3., and 4. -- Just chicken and egg FUD.
Not to mention it's "'Better X' doesn't matter" fundamentally doesn't understand the competition.
A sample quote: "That's not just one but eight(!) killer features (re: Java). How many of those unique selling points do the C alternatives have? Less than Java did at least!" WTF?! "But Java had 8!" is laughable.
Another: "[A]ny safety checks put into the competing language will have a runtime cost, which often is unacceptable". We can also produce a car without windows, doors or a chassis that will survive a crash, and it may be faster too. We may even get lucky and live to tell the tale.
Again: "Aside from Jai, is anyone C alternative really looking to pursue having killer features?" Aside from Jai?! Jai. Really? Oh, I remember you just discounted safety and correctness as killer features. ... But Jai. And nothing against Jai. But a language which hasn't been, which may never be, released to the general public. Just, eyes wide open, wow.
I hope this is the peak of anti-Rust/pro-C silliness, but I know it's not.