Single UI applications in Flow. Support for PreserveOnRefresh

Is there a way to build single UI (single Page) applications in Flow?

In earlier versions of Vaadin, it was easy with PreserveOnRefresh annotation. Is there any plan to support PreserveOnRefresh in future versions of Flow?

I just noticed that PreserveOnRefresh feature is planned in Vaadin 14.
[https://github.com/orgs/vaadin/projects/1]
(https://github.com/orgs/vaadin/projects/1)

You can also find some relevant discussion here: https://github.com/vaadin/flow/issues/3522

-Olli