The only way to have any idea of how long a language might be still around is to look at how long it's been already around. From this perspective , you can only use older languages. The benchmarks show that Lua (and the Luau and Lua+JIT variants) is actually very competitive, so I'd stick with one of those.
In the end, weight is a kind of strength, and popularity is a kind of quality. It looks promising but you can't expect long-term support until there's more contributors and users
At this point it is too early to know. Even JavaScript took like 20 years to catch on