Cessna left piston production because they could make much more money off one bizjet than dozens of single engine piston a/c combined. Liability was just a good PR talking point.
If that was the main consideration, why would Cessna be producing 172, 182, 206 today?
40 years ago, I was able to buy 450HP for $11,000.00 of fully certified and very useful shiny new aircraft engines. I would LOVE to be able to do that now, but harsh reality is we don't do wars that run on recips these days, so it is back to the drawing board. IMHO, the ONLY two ways of getting a lower cost airplane engine is to do an automobile conversion (and we have seen those since old Henry's days...even the V8-60 was actually certified with a reduction drive) and you can see the cost of those by the pricetag on Thielert (bankrupt, now Continental) 135, 155, 170, 300 HP engines that cost about the same per HP as their bespoke direct drive new airplane engine (265). I suspect Austro has about the same values driven by actual costs. The second way is to find an alternate use for your new engine design that has a LOT more volume than aviation and try to get costs under control that way. Think of the Lyc O-290 as a GPU/genset/etc. as how to do that.
I think the people doing Honda, Suzuki, etc. auto engine conversions are on the right track for E/AB, but not sure they are going to make it into the certified world. Remember what the results were when Porsche tried that? I think Limbach came as close as anyone to ever pulling that one off.
Personally, I can't see using gasoline as a motor fuel (ridiculous stuff, and dangerous), so my salvation will have to arrive burning heavy distillate fuels (jet and diesel). Until someone figures out how to make a Rotax 912 weight and power engine for low enough bux, I can't see it happening.
IMHO: the real breakthrough will come if we increase the LSA limits to 3,000 or better yet 3,600 lbs. That is IF the FAA can keep their nose out of it and the government can keep the LLL away.