There's an old saying. "Don't borrow trouble". Don't worry about things that may never happen. Enough actual problems come along for us to spend our time worrying about.
Solus is only created for desktops, so the community is mostly made up of people who will not be able to contribute
That's true of pretty much every distro that doesn't have a large company backing it, regardless of if they are desktop or server oriented. There seem to be developers available to contribute. Also, development isn't the only way to contribute. There's testing, documentation, and other ways.
The irony for me is that I just became a contributor to Solus (I'm working on updating pidgin). People leave, people join, that is the way of all distros. I've contributed to other open source projects with bug reports, testing and general feedback, long before I started writing code for a living. I write automated testing as a QA engineer.
In that role, part of my responsibility is to weigh the risk of something breaking and the likelihood of it breaking as part of risk assessment. It's a skill that's really beneficial generally, and in this case specifically. I'm being generous and assuming you want to know how likely it is Solus will be around long term because you want to use it. It's reasonable to want to be relatively sure that something that will be a daily driver is going to be stable and not just disappear.
So things you might consider if you're evaluating this risk for yourself, first consider how stable Solus is:
- How long has the distro been around? (You can check the Solus repos to see how far back the code goes)
- How actively updated is the distro and its applications? Again, check the code base.
- How active is the community now? Look at these forums, and the IRC channel. It's very active.
- How many core developers are there? How many other maintainers? (Check the repo)
Now for the "negative testing", or how likely it is that Solus could die:
- Are there too few core maintainers? (For instance if there were only one, then if they are suddenly no longer available, the project is likely to die. With more maintainers, the likelyhood goes down)
- How many people would need to leave before the project becomes unmaintanable by the people who are left? After you've determined the amount of current maintainers, you can answer this.
- How many people join vs leave over time? (Not just core maintainers, but package maintainers & all the rest)
So, there are some ways you can try to answer this question for yourself. In the end, either you feel Solus is stable and reliable enough to use, and you use it, or it's not and you don't. Happy hunting.