It's hilarious how desperate they were for any scrap of product to announce. 18 months+ later and still not a hint of a go live date. I'd not be surprised if Blizzcon stops being annual
That may have something to do with just how much time it takes to develop new AAA games these days, but you would hope with more live service games that they could do more regular, smaller content drops
As far as I understand the mobile Diablo was supposed to be contracted out to another company (Netease). Said company also has a - let's put it this way - very similar game already on the market.
So I guess it's even more surprising there haven't been any further news since then.
Unless of course, they pivoted the project, to provide a PC version or a different game altogether.