There is a sizeable market for passive and not much competition, so I suspect they can make some money on this which is why they intend to do it.
Or, add fans to fully passive solutions like this for outstanding cooling performance.
I agree there is a decent sized market for passive, but that market is divided into two main segments
1. Hermetically sealed for workshop/industrial/volatile environment.
2. Prosumer/Consumer wishing for a) silence and b) zero-maintenance cooling
This cooler does not serve the first segment at all, since it can only convect heat around internally, you need heatpipe-to-external-surface for that.
Consumers wishing for silence are likely going to be using this in HTPC scenarios or recording studio scenarios. There may be other niche use cases but that covers the vast majority of the 'silence' angle. For recording studios etc, the size of the PC is less of an issue so this would be a reasonable solution when paired with the right case and components, but again, the instant you put a single fan
anywhere in that
room, a passive CPU cooler is pointless because you can put a fan of equal noise level on everything and get away with near-zero increase in dBA level, assuming those fans are even above your noise floor in the first place. As for HTPC users, both the size
and orientation of this Noctua cooler are largely incompatible with the majority of HTPC-specific cases. If you have a desktop tower as an HTPC, sure, it'll work but that's a pretty janky setup and most HTPC users with janky setups aren't going to be spending big money on a cooler when there is much lower-hanging fruit in their setup. That example customer is effectively an oxymoron.
Consumers wishing for zero-maintenance dust-free operation in a desktop case large enough for this Noctua is definitely a niche I can see this being used for, but we're talking low-end GPU with a full-passive cooler (the one pictured can probably dissipate no more than 100W in a fan-free case, and that's being very generous!) full-passive PSU, convection-only case design, ideally with vents at the bottom and top of the case only, and some kind of dust cover on the top to stop dust ingress due to gravity. I don't know how many customers that really applies to, but there must be a few. Once again, the INSTANT someone puts a single fan into a case like that, the whole argument for that setup falls apart entirely. The finest mesh dust filters for intake fans are extremely effective and easily cleaned in seconds, totalling a mere few minutes a year even for the dustiest of environments. but once you have a fan in the system sucking in outside air, there's no penalty for adding more, which instantly nullifies the argument behind a fully-passive CPU and GPU.
So whilst I'm not denying there is a market for a very large, fully-passive CPU cooler, I'm questioning what I've missed in terms of how small the target audience is likely to be, and how very little the target audience has to change to get a superior, cheaper, easier solution anyway.