I think the biggest factors in adoption are: being in the right place at the right time and app/platform exclusivity.
That's a lot harder to overcome these days. I'm starting to doubt if we'll ever see another popular language displace the status quo.
Programming languages are simply interfaces into a particular tech stack. The stacks will shift as the trends come and go, and the languages will go with it. Perhaps the lowest levels of the stack have settled nice and snugly, with little hope for displacement except by extreme measures (cpu archs, kernel/os implementations, etc) but the higher layers are still rapidly changing, and dragging along new languages with them.
That is, kernel devs got into bed with C before it was a "clear winner", and now they're stuck with it.
Ecosystems that are still developing, layered on top of these older more stabilized systems, have the freedom of choice, and they certainly make use of that freedom.
And of course, by nature of a non-stabilized ecosystem, most choices made are done before a clear winner exists -- because no clear winner exists just yet. But the choice will stick, unless it was dramatically harmful to the project.
The older the ecosystem, the less viable it is to select anything other than the clear winner, because the ecosystem is coupled to that clear winner, and the ecosystem is the fashion.
That excuse reflects very poorly on the planned future of the company I work for, but I don't think my bosses recognize that.
It's apparently less important that our applications are crash-resistant by design of the platform rather than the application itself. I'll admit I'm a bit of a diva with regards to available tools but it's getting really tiresome.
That sounds a bit the end of progress. After all, Go, Rust, and Swift haven't been around for that long.
I might be open to an argument that ecosystem effects (libraries, training, etc.) lead to power law effects. But I'm not sure I believe that. I could equally well believe that the sheer scale of software development today lends itself to a lot of viable niches.