No, but I posted it last year in a DevDiary thread, so by now I assume that a number of devs has already seen it.
While I don't expect a 1:1 implementation (for that the idea is still too rough), I do hope that they like the estate system they created enough, to consider doing more with it in the future. So the mockup is more of an inspiration thing than a specific and well thought out suggestion. That often works better with creative jobs, than to tell them what to do.
Good news is, now that the Mongols do actually use this UI for all of their nomad holdings, it tells me that the journey is going exactly there. You can see that the old holding screen takes an absolute backseat in the new DLC:
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I'm rather pleased with the direction. The holding system, together with the army management/manpower system, are the two major mechanics that I want to see remade entirely. Trade, republic gameplay, and the lack of the rest of the map, those were the other three, but the writing is on the wall for those.