This was stated in the Item Factions dev blog:
In the most recent dev stream on March 17th Mike noted that development on these systems has yet to begin.
Though, Judd stated this on March 11th in the in-game chat. However, take this with a slight grain of salt as he did state this prior to their scheduled meeting to plan the rest of the year in detail. It was more of an off-the-cuff response to people in chat rather than an official date, in my opinion.
https://i.imgur.com/CYByYeP.png
However, if they do follow this and they return to their previous patch cadence schedule, as they’ve stated they would (which is every ~100 days), then patch 0.9.1 would be ~June 17th (though they may push it back a week or two because of Diablo 4 so probably closer to June 23rd or June 30th) and then from there we have ~Sept. 29th to Oct. 6th (give or take a week) for patch 0.9.2.
Again, this is all very hypothetical and we’ll have to wait for more official news about the release schedule for these systems in the coming months ahead.