will this be fit for ssr in the future?
This may not be what you're looking for, but RawJS kind of already does SSR in a way, check out StrawJS. It's a tool that returns RawJS into a static site generator of sorts. RawJS works with DOM simulators like HappyDOM / LinkeDOM so you can run it in NodeJS. Though this is more "developer-side rendering" rather than server side rendering.
There are some plans to move in the direction of SSR, but to give a proper answer I'd need more clarity around what problem you're trying to solve. A previous incarnation of RawJS allowed for things like server-side DOM event attachments that would reconnect automatically during page load, but this hasn't made it over to the current iteration. (And if it did, it would some in the form of a separate library)