Our road ahead changes all the time, so we don't share concrete specifics until we're confident we can commit to it in the near future. The only way to get our road-ahead thinking would be to attend the Runtime Road Ahead sessions at Devsummit or User Conference (note that these sessions are never recorded for the same reason).
However, feel free to request functionality in the forums. We do listen here, and it does help us putting things in the backlog or re-prioritize.
As mentioned before StreamingLayer and GroupLayer are in our backlog, but I cannot make any specific commitments to those at this point.