> So Google is officially making its stand as Dart being the future of Android (the Swift of Android?).

It's almost never accurate to use "Google" as a singular noun. We are a very large company, and teams are given much wider latitude than at most other companies, so there is rarely a single official "voice" representing what Google is doing.

Instead, you have a lot of teams each working to make the best thing they can. Some of these projects overlap, sometimes they coordinate, occasionally they even compete with each other. Google is big, and the world is even bigger. There's a lot of room for different solutions to problems.