Exactly why any company that cares about long term maintenance should stick with Node.js except in cases that justify alternative runtime.

I wouldn't be surprised if Bun is abandoned at some point as well.

(Which is why I am happy to see new runtimes but never care enough to seriously use or adopt them.)

As long as the competition forced Node to become better then it's all good.

Communities aren't always in competition with one another.

Yes they are. If opensource product A does not have better features than competing opensource product B, uses move to the better product A and pretty soon, almost nobody will use product B. Take BSD vs Linux for example. We get "we've migrated to BSD" or "we've migrated to Linux" posts all the time and arguments for one or the other. Is there a winner and loser? Yes. Larger communities, more developers, more corporate sponsors, more contributions, etc. Certainly looks like competition to me.