No it isn't. The probability of two independent events don't multiply. Multiplying is two events occuring together. You only need one here for a failure.
My disagreement is as follows;
both must occur to work so they multiply to get success rate of 98.01 after 1 year.
so 99 percent success multiplies by 99 percent success giving 98.01 percent of the time they will both work after a year.
You could say that but it is largely a diversion.
All indications so far is that this "move files to faster media on same volume" is the primarily the same mechanism that is already in place. It gets invoked already on HDD and SSD drives (although not really necessary much of the time on SSD so less frequent. ). There is different data being fed into the same basic heuristics ( it may move more or less now) but failure is in terms of loosing data not optimization level. That isn't going to be any more prone to failure now than it was before so is largely part of the nominal background risk.
Your the one who is asserting "perfect" software. There are software failure modes with or without Fusion.
Similarly a write driven cache. There are block caches in the OS now. This is just a variant on the fundamentally the same mechanism that is extremely lacking in failures now.
Throw on top that Apple so far is really only pointing this being done with their drives means there isn't any unknown, untested configuration that is gong to pop up. Software isn't like hardware. If run the same config then get the same results. If a defect is found it is a "find once fix many" context. Over time the probabilities go down unlike hardware where getting different component failures due to physical effects.
Software components like file systems where system wide data integrity are at risk are typically tested far more rigorously than "normal PC" application software.
If Apple had thrown out File Vault 2 and Fusion last year on top of a relatively new Core Storage framework perhaps this "version 1.0 software" boogeyman you are trotting out here would have more legs. They didn't. Similarly if File Vault 2 surface with several integrity bugs ... again didn't. They have actually held back on aggressively using the features. That is highly indicative that this isn't a "ship it even with bugs" kind of software project.
I also disagree with your software assertion. right now the 2012 minis are having a driver issue with the integrated gpu. So they tested and I would guess they decided the screen black outs for under a second at random were okay enough to sell as the "we need to get this to market we will patch later". Mentality took over.
Just think apple maps. Scott Forstall
"DaringFireball's John Gruber believes that Forstall was forced out of Apple:
Forstall is not walking away; he was pushed. Potential factors that worked against Forstall: his design taste, engineering management, abrasive style, and the whole iOS 6 Maps thing. I also wonder how much Forstall was effectively protected by his close relationship with Steve Jobs — protection which, obviously, no longer exists.
Inside Apple author Adam Lashinsky agrees with that sentiment and also cites the Apple Maps issue as a reason for his demise:
I also heard that Forstall refused to sign the letter apologizing for the mapping fiasco, sealing his fate at Apple.
Lashinsky is referring to a public apology posted by Apple CEO Tim Cook about iOS 6's Maps. The Map app in iOS 6 replaced Google Maps with Apple's own proprietary solution. After a significant amount of criticism after iOS 6's launch, Cook wrote an open letter apologizing to customers about not meeting expectations. "
the quote is from mac rumors article
https://www.macrumors.com/2012/10/29/scott-forstall-reportedly-forced-out-of-apple/
Look the idea of fusion is stop gap and already too old as ssds are just getting cheaper.
What will happen is ram plus ssd will be the goto not ssd plus hdd
and real speeds will be achieved. this tech is already being done with pc's
http://forums.anandtech.com/showthread.php?t=2279821
this can be done with a diy pc pretty easily makes fusion look like molasses.