Too soon to say about a full app, but we don’t plan any release soon, as Sketch is a very powerful studio and gives plugins like ours a great freedom.
As long as this approach continues, we would love our users to start in their home court and continue online.
It doesn’t mean you won’t see these features inside Sketch or on our website, as we do add more online tools :)
As for custom code, we will add more power in the upcoming releases. You may already add a script that goes to all of your pages, like counters, online chat plugins, etc. You can do it from the Manage Website panel.
Exporting code will also arrive soon, no worries :)