imho it makes sense to focus more on further improving dart2js to ensure it works really well across all JavaScript virtual machines and to make interop with JavaScript & TypeScript super smooth.
The Dart VM (as well as the Observatory) are fantastic. At Blossom (https://www.blossom.co) we currently use the Dart VM for command line tools but we're looking into using it on the server side as well.
I guess you were especially interested in the performance improvements that the Dart VM could bring if it was added to Chrome? I expect that we'll also see performance improvements for dart2js as JavaScript runtimes become better compilation targets (e.g. SIMD.js, BigInt, SoundScript, …).
The interesting thing here is that the Dart team can focus on other areas like …
* the standalone Dart VM
* fletch (an experimental mobile optimized runtime)
* Observatory
* async/await
* libraries (e.g. the new `test` package)
* analyzer (used for semantic code completion & warnings and powers IntelliJ, Eclipse, Sublime, Atom (soon), DartPad see https://dartpad.dartlang.org/)
* …
and many other things in the meantime. Getting the Dart VM into Chrome and have it play nicely with v8 is not trivial.
When there is no Dart VM in the browser I honestly don't see any advantage over TypeScript. Two VMs inside each other (with two garbage collectors) will always be slower and use more memory than just one. Additionally, you always need to ship the runtime with all your scripts. You also have to use FFI to interact with Javascript. All the advantages over plain JS you mentioned above are also present in TypeSctipt (or not needed).
What second garbage collector are you referring to? There aren't "two VMs inside each other" when you compile with Dart.
I think Dart's biggest weakness is the fact that most web developers don't understand how compile to JS languages work and go around spreading all kinds of silly FUD. I remember posting a Gist on the day of Dart's release showing the compiled runtime, and the thread exploding with hundreds of comments from people laughing at the fact that it was 17,000 lines or so, nevermind the fact that that's how every compile-to-JS language that's more than a thin skin over JS semantics works.
TypeScript is definitely an improvement over JavaScript but it is less ambitious compared to Dart (something that is also mentioned in the video you linked to).
Dart is more than 'just' a language with cleaner semantics (which is already an improvement upon TypeScript which still is closely tied to JavaScript re type coercion problems etc).
See my other posting. The Dart VM exists and can be used on the server side, for command line apps and in Dartium (fast dev cycle & debugging).
There is advanced tooling, a very clean standard library, a mobile optimized runtime, bundler inspired package management (pub), a well staffed team of people working on the analyzer and compiler toolchain and a lot of stuff surrounding "Dart the language".
