At the moment that is absolutely no roadmap for node-red-dashboard beyond angular v1.
There are community efforts (uibuilder, FlexDash and others) to create dashboards projects.
In terms of what happens to node-red-dashboard - we don't know.
There are simply so many directions it could take (as demonstrated by uibuild and FlexDash). Each has its pros and cons and there are still lessons to learn from node-red-dashboard. I don't know if we'd look to 'adopt' one of the emergent dashboards as the natural successor to node-red-dashboard, or just let the community choose for themselves what fits their needs.
