Part of the problem is that this V8 engine is a 2x improvement. It's definitely an improvement, but a sub 10x improvement isn't enough to bring on a revolution. The article alludes to investors' lack of appetite for the risk, I suspect a larger improvement would convince them.
If he actually got this V8 certified and Cessna switched to then it might be dirt cheap to run but the 172 with it preinstalled might be $1M because they will sell so few and have so much engineering & certification cost to amortize.
That's how silly it all is, and why it will stay stuck in Experimental.
VLJ's are cute, yes. I'm slightly hopeful about small scale turboprops too. Yes, generally turbines don't scale down very well (well, applies to VLJ's to an extent as well), but if they only could make the capital costs of a turbine decent enough, the reliability, power/weight, and cheap and available Jet A-1 would still make such a thing attractive, I think.
There's a couple of companies working in this space:
