I once heard of a description of a system for explaining to people how features in software are delivered. First you make a big list of all the planned upcoming features. Then you prioritise the features in order -- the most important/desirable one on top, then the next one, and the next one, etc, etc. Then you change the opacity of the lines of text. The top line is completely opaque. The second one is slightly transparent. The next one is more transparent. You increase the transparency as you move down the list.
The software features are *not* delivered on a schedule (because stuff happens and priorities change and whatever). However, the list shows you the probability that you will see the feature in a timescale that is relevant to you. So the top one is practically 100% because I'm working on it right now. The bottom one is practically 0% because at the moment I've prioritised *everything* above it.
Asking about the ETA for X is not useful because in reality you are unlikely to actually see X *at all*. Software isn't built to some grand design. When we write software, it's virtually always bespoke development of something we have never built before. It's not like building a house where we've build 1000 just like it and we're only tweaking the design. The thing we are building *might* be superficially similar to something else that already exists --- but probably not (because it would be orders of magnitude cheaper to simply use a copy of that existing thing --- unlike a house).
Things change in software development; often dramatically. Just look at iterations of dwarf fortress's development list. It changes over time.
All that to say, instead of saying, "When will I likely see X", you should ask "Am I likely to see X". For this particular thing, it's not on Toady's priority list at all for the next several years (which is being taken up with villains and myth and magic). So the answer is "No", you are unlikely to see this in a time frame that is useful to you. If you ask "Am I likely to *ever* see X", I'll give you a similar answer. "No". Toady's been doing this for a long time, so hopefully he will continue to do so. But stuff happens and X years is a *long* time away. If you asked me 10 years ago what I'd be doing now, I wouldn't have given you even *close* to the right answer.