I understand the concept of open source. But heretofore I've not done any coding - or maybe I should say I've not coded in anything that would be relevant. However, if there was a repository of vetted coding I might be interested in trying some of it. But "checked out" means someone would have to test it and give it a rating or somesuch.
As for running my own instance, no thank you. I don't have the infrastructure with which to do that. I'd rather Nabble continue to do that. But if that requires some annual fee in order to make Nabble viable then let's talk.
I am a great believer in open source software and reckon it is perhaps the only way to keep a software project alive especially where that software has a diminishing market.
Since the development of the major social media and blogging platforms and the development of "no coding required" web site builders such as WordPress, Wix and Weebly few people need an embeddable forum these days.
Having followed this forum for a few days more than eight years I would think we have have lost the opportunity to take advantage of no more than half a dozen people who might have spent some time as core programmers with the project. My experience with an open source project I started in 2002 suggests that some would only take a passing interest, develop a particular feature and then disappear again, so I do not believe that going open source, in itself, would attract a significant number of programmers to the team.
The project I started was a plain text email program (like a forum these days, a specialist tool in a diminishing market) It continues to this day, although I have been less involved over the last four years. My efforts were entirely based on documenting the software. Indeed the programmers all approached me after I produced some initial English user documentation of the extremely crude Japanese original.
I have no modern programming skills beyond HTML and CSS. (I was fine in BASIC and Z80 Assembler back in the 1980s, but since moving to CP/M and DOS I found all the software I needed already available and never got beyond doing things most folk considered magic with DOS Batch files.)
So, to answer your specifics...
Good idea? Or not?
Good idea! It could be the only way to keep Nabble going.
Would you contribute code?
I'm not capable of offering anything to the core program, but I would continue to do what I could in documenting the project and providing CSS templates.
Would you run your own instance of Nabble?
Should Nabble cease to operate its current hosting service then, almost certainly, YES!
I host about a dozen sites for various personal purposes and non-commercial organisations. Almost all include a Nabble Forum, Blog or News app. It would be far simpler to run my own instance of Nabble than try to learn and run a dozen different independent platforms. The huge advantage of Nabble is its "node-based" approach and the flexibility the offers for presenting content in a wide variety of formats.
Maybe Nabble needs to adopt the WordPress Model and provide a crude advert-funded hosted forum at Nabble.com, with various paid-for options such as going advert-free or adding more than a certain number of sub-forums or displaying in Blog or News formats and also run an Nabble.org where the programmers would hang out and folk like me could develop CSS templates that could be offered as add-ons at Nabble.com and download the whole thing to run on my own server.
Just a Volunteer Nabble Helper - because the nice folk at Nabble have helped me! GregHelp - Building a set of answers to Nabble FAQs.