Wonder if the main (only) SB developer of the Score Editor Michael Michaelis, is still inclined to put more skill/magic into this (it’s his ‘baby’ alone), considering there’s an almost inevitable future of Dorico working closer/integration with Cubase.?
Just setting expectations a little… 
Most of the time I use musicians, I’m using the score editor to make parts. It’s the best I’ve seen in any DAW, and a HUGE time saver once you wrap your head around it’s power features.
The only exception to this is full orchestral scores, where I need dedicated software like Dorico to do the heavy lifitng. But I hope the score editor basically stays as it is for awhile longer.
I think that is the exact scope for which it’s meant – even multiple parts.
When things get really big you need to be a Maestro 
to manage.
In my opinion I think it will, for the very reason you hope. I also believe there are many, many Score users who do not post in forums.
I admit that I don’t use the score editor in Cubase much. From playing around with it though, there’s not much you can’t do in it.
Ok, the workflow of a notation program is obviously better. (Automatic setup of transposing instruments, divisi, collision avoidance, engraving rules etc etc.) But since this program often costs as much as Cubase, I’m not sure if it would be a fair expectation for these two programs to “integrate”. Maybe I’m not grasping the exact meaning of the word here, it’s very possible.
At most, I expect that in the far future, I will be able to edit the MIDI data of a track on the version of Dorico that I currently own (be it SE, Elements or Pro), maybe in an extension window, like ARA.
But a behemoth like Dorase, or Cubico, (or Cubendico if we also entertain the thought that Nuendo is a premium Cubase), I can’t even imagine how one could manage this type of product. How do you sell it? How much? How do you chop it into tiers, and what do you leave out from each tier? 
Edit: Cubendico has a “premium aged rum” feeling to it though…
While it is true that Score Editor will not evolve, I hope that there is a deep relationship between Dorico and Cubase in terms of interchange, integration, etc. at least as is the Score Editor with Cubase: merged!