I'm pretty sure "wear on the spark side" is an all but solved problem at this point. Most car engines made in the last 15 years have 100k mile lifetime on the entire spark system.

I know for more recent vehicles that is probably true, but as an owner of a 2006 F-150 with the 5.4L 3V Triton V8 that had the infamous spark plug issue, I had to lol with a tinge of sadness at your "last 15 years" comment.

Backstory: Ford came out the gate with a new spark plug design for the 2004 F-150 3V Triton 5.4L V8 engine (after their previous spark plug design failure in the 2V Triton where the plugs would shoot out) and told everyone that the spark plugs would last 100k miles. Turns out if you let them go that long, they would get stuck in the cylinder head and break off when you tried to remove them, leaving stuck broken pieces of spark plug behind. Conveniently, 100k miles happens to be when most people's warranty expires, leaving people with a best case a few-hundred-dollars-extra tune-up bill, if not thousands of dollars if the heads had to be removed. Ford faced a class-action lawsuit over this debacle, and there are still companies selling special broken spark plug removal kits designed solely for this engine to this day. Of course the root cause of the problem is faulty design, but it would have been mostly avoided had they not claimed a 100k mile service interval for the plugs. So yes, Ford went from an engine where the spark plugs would shoot out of the cylinder head, to one where they would get stuck so hard they would break.

I know all of this not because I am an engine geek, but because it happened to me. Two spark plugs broke off while being removed and I came this close to needing to have the heads removed and machined. Fortunately those special removal kits I mentioned earlier really do work. Given how relatively cheap spark plugs are, you can bet it will be a while before I trust that 100k mile number :-)

Well, that's sure unfortunate. I care for my father in law's focus, and the iridium plugs really were good for 100k miles. In 35 years of caring for cars I have never been so frightened by the sounds and feel of unscrewing a spark plug though.

This is the one with a "permanent air filter" so they were thinking about eliminating maintenance. Boy this is going to suck when it is clogged.

I agree that for the most part engines are extremely reliable. The potential downside here is that the compression mode makes the entire system more complicated. This might make the new system less reliable. I have every confidence that Mazda will do this right, and this has great potential to extend the lifetime of the ICE. However, it isn't without risks.