Speaking personally, Datasette is the first project I've worked on in my entire career where I'm confident that I would be delighted if I was still working on it in 10-15 years time.
The space it operates in - analyzing, exploring and publishing data about the world we live in - has completely limitless appeal to me. Every project I've ever cared about can be attached to it, especially given the plugin architecture which supports me trying out all kinds of weird and interesting applications for the core technology.
If I can't make it work financially it can go back to being a side-project for me. I'm confident the financial side of it can work though.
I feel the same way about cloud custodian and starting stacklet, but I also put stuff into a foundation, so that it has proper survivability beyond the org, irrespective of the org's decisions (Ala hashicorp), and true survivability and impact on an oss project means getting past individual contributor bus factor.
That's a bus factor of 1?
You know what's more cool though? A 100 years: https://archive.is/qnWWX (didn't work out all that well for Evernote, regardless). I'm sorry but this script has been sequel'd over again and again. May be, just may be, you're a unicorn (:
1. Trust over a product or platform can be formed in many ways. Opensource is an irreversible way of doing that. I have often seen people equate opensource to free usage of the product, it is great for adoption but very bad when it comes to monetization. Even if your project is available as OSS if you don't have community around it, disappearance of the org is still a threat.
2. If there is no market, you don't any incentive to maintain it forever. Google fusion tables is probably that case. The market perhaps was not large enough.
3. I do buy into incentive to opensource for building an eco-system
4. I do buy into the larger impact argument but question is - will you keep maintaining it if there is no incentive for you in the process?
I have seen lately, lot of VC backed orgs posting OSS as a differentiating factor than their competitors. I am not sure if I would buy into that argument.