I also know scientists for whom a page covered with sets of five lines covered with funny symbols is a rather frightening sight, and can’t understand how some people can actually make sense of it in real time 
It’s between Dorico 3.5 and Dorico 4 now. I wonder how this topic is being treated in Dorico team at this moment.
Interesting thoughts about TeX (I barely graduated to that new fangled LaTeX!). It was my first documentation system so I know and love it well.
But despite its myriad of engraving rules and algorithms, Dorico is a WYSIWYG application. LaTeX doesn’t seem to fit at all into the concept, does it?
No, actually Dorico isn’t WYSIWYG, but is document based like TeX/LaTeX. Think, you enter your intentions and Dorico handles the formatting. Sure, before somebody mentions it, you can side step that and force something to be here or there, but you can do that also in TeX - but in both, 99.99% of the time you don’t. And yes there is absolute positioning in Dorico (e.g. with frames) but TeX also has that. So really they’re remarkably similar, except Dorico is so good as to fool you into thinking you’re in a WYSIWYG app. It’s funny too, a lot of the questions on the board are “why can’t I?/why does it?” ones related to this paradigm.
So yeah it would be between a nightmare to impossible to marry the two, as I’m sure the layout algorithms are completely separate. Instead just create little graphics, or PDF’s->SVG’s from LaTex, then put them in a graphic frame. If Dorico supported links - which is when the file changes it auto updates in Dorico, that would be all the make it seamless. Kind of like an ‘inverse graphic slice’ - one that works in reverse wit graphics frames.
And on the supported font technology, as Daniel says it really depends on Qt, it would be foolish for the team to spend resources to try to work around any limitations. Energy would be better spent lobbying the Qt team.
There is no reason to expect there to be any changes in this regard until such time as Qt implement deeper OpenType feature support in their framework. I don’t think it would be a good use of our limited development time to try to implement this in Qt ourselves, even though I agree that there are many OpenType features that it would be useful to have in Dorico, not only for CJK text but for other scripts as well.
As it seems like OpenType features support isn’t coming for some time, I’m curious — has anyone developed a workaround, to get, say, true small caps in Dorico?
Of course this isn’t the solution you’re asking about, but I mostly use Minion Pro, which has dedicated small caps in its font set.