As we have seen in most milestones, Kotlin is gradually moving closer and closer to Scala, because even they realize that "a slightly better Java" won't cut it in the mid-/long-term.
I wouldn't call it "slightly better". It is much, much better. There aren't that much changes to your programming habits or architecture, but improvements which Kotlin brings are huge.
Absence of nulls, type-inference, top-level functions. All this would make a huge difference, not "slight" one.
You would be surprised what's out there.
Kotlin is an attempt at taking the other road: building an incremental language over Java. We'll see in a couple of years if that experiment is a success.
People who think that – in the end of 2015 – everything we need is a slightly nicer Java show an scary lack of insight and vision.