Will Sync ~~sorry~~ support all of the new features of 0.19?

I suppose that eventually it will, like the ability to manage blocked instances at the account level (instead of at the app/filter level), the ability to select a specific language label when submitting a comment or post, etc. It already does some thing that 0.19 does, like new comments highlight.

That entirely depends on @ljdawson's roadmap.