Your LinkedIn investigation is correct. :) Lars, Gilad, and (more recently) Kasper are not working on Dart anymore.
Dart's been around publicly over six years and existed privately for a while before that. That's a long time to work on one project, especially in the very fast-moving world of software. Change is natural and healthy. If you look at things like commits on GitHub, you'll see some people have left but also lots of new blood on the project too.
The language design is currently co-led by Leaf Petersen and Lasse Nielsen. The spec is maintained by Erik Ernst. Those names should be familiar from various talks and email threads, so I hope you agree Dart is in good hands. We have a rotating cast of characters from the larger Dart team who work with the leads on designing and implementing various language features.
I'm personally more excited by the current team structure than I have ever been during my time on Dart. We've got a great group of smart, focused and well-aligned people driving things, and I think the most recent DartConf is an honest reflection of that fact. I'm super excited about what 2018 is going to bring for Dart.