Absolutely.
The thing that this allows (and the companies that inspired this stuff, e.g. GitPod) is to codify your development environment - similarly to what has been happening in the infrastructure world. And I'm not talking about editor configs, but the entire toolchain.
Of course, if you're just working on one main project, or a few with a shared toolchain, this won't be adding much value for you. But as soon as the matrix between development environments and projects get bigger, this becomes a huge productivity boost.
Think about a mobile (as in, moves around a lot) developer that uses many different devices - there's no additional work to keep those environments in sync, or set up a new one. It will just work in the browser.
Or a bigger company with many projects and many people (think devops) that need to jump into different projects all the time. I don't want to waste my time setting up the specific toolchain for that project, or even check it out - I can just open up a pre-configured, guaranteed-to-be-working dev environment in the browser in a few seconds and get going. This would by my personal use-case, and I'm super excited to see this happening.
I was already thinking about setting up GitPod for our company GitLab, but if GitLab manages to combine the GitLab CI/CD Runner Session feature with this IDE for background tasks (compilation, terminal, etc), you would get 90% of the awesome-ness of GitPod for free with your regular GitLab setup.