Considering that Java still has about 95% market share on the JVM, I'd say Scala has a long way to go before it can catch up to Java. Same observation for jobs and tooling.
The grandparent asked explicitly about Java 8 and 9. What are the market share, jobs and tooling like for those versions?
As someone who's had to push for both, many organizations find introducing Scala easier than doing a JVM upgrade (since the latter requires work on the ops side). Last time I looked, e.g. the New Relic agent would crash if you tried to run it under Java 8 - whereas it will profile your Play transactions just fine.
Popularity is a lagging indicator. The tooling is there already, quite frankly - we see first-class support for Scala in new efforts like Takipi. Jobs are what you make them - more than once I've taken a Java job and turned it into a Scala job. I honestly believe it's the best general-purpose language going right now (which is why I use it, and why I have a job doing it full-time).
It really all depends on what criterion you use.