A modern programming language that makes developers happier.

kotlinlang

Java catching up is definitely a risk, if they maintain compilation speed. 

I don't think it is. At a fundamental level, there's a lot of design decisions that are different between the two, which for most people make Kotlin the more favorable choice.

I’m talking more about server dev teams having less incentive.

Not a “do or die” either, but it’ll have some impact. However, kotlin has done well in part because it’s not risky to include it. Interop with java is great. Same with native (soon) flutter doesn’t play well with either native platform. It’s a risky option