I dont' think that really matters. If Flutter solves the cross platform issue, people will deal with Dart. And if Flutter sucks, nobody will put up with it sucking just because they love Dart. Either way Dart isn't the big picture, Flutter is.

I disagree. I would not recommend flutter to anybody precisely because of how bad Dart is. It's such a productivity/maintenance drag that the framework is not worth it.

Dart is much more similar to C# than JavaScript

It's the worst of all worlds TBH. It has terrible reflection and metaprogramming capabilities which leads to ridiculous solutions like code generators at every step. Type system is super weak (eg. it just gives up on type checking ternariea for eg., had multiple runtime type errors because dart couldn't catch it at compile time), but at the same time also closed and very inflexible. Working with immutable types is ridiculously bad compared to C# or JS. Serialisation is terrible as well.

Flutter would have been a much better framework if it was built on typescript