So assuming the time jump theory is correct, which right now it seems to be, Nhan will also be on Discovery season 3. But why and how do Georgiou and Spock get off Discovery before the time jump next episode...
Why do you assume either one will? (I honestly believe that IF they do a story of the U.S.S. Discovery in Season 3; at some point they will return to the 23rd century again. I don't think they're going to pull an 'alternate timeline reshape of history' trope to explain why TOS looks like it does - they are and have been saying "Look, this is the TOS era now".)
And yes, while (if you look at my posting history) I'm honestly annoyed with the exterior 1701 CGI model nacelle struts design (I have trouble believing that the ship when from the straight single strut look in "The Cage" to this look, then BACK to "The Cage" look for TOS S1 - "Where No Man Has Gone Before" and then the look we all know - and I STILL LOVE - for the rest of TOS - well, TOS 'remastered' -

)
I'm an old school fan who's loved Star Trek since I first saw it on NBC (in 1969 - I was 6 years old); and I GET that for what they were going for they need to 'modernize' the look of some aspects for 2019.
I LOVE what they did for the interior of the 1701 Bridge in this episode; and I think they did a much better redress of the Discovery corridor sets to make them more 'Starship/Constitution' class than the Door to Spock's quarters in ST: D S2 - "Brother"...
But sorry, I have never understood the problem anyone had with the TOS era Starship/Constitution exterior model as it looked great in ENT S4 - "In A Mirror Darkly 1 & 2" (Yes, it was the TOS era U.S.S. Defiant but still a Starship/Constitution Class ship); and it looked well re-rendered in TOS Remastered.
And again, I'm okay with the majority of the changes they did for the exterior model of the 1701 Enterprise - with the exception of those nacelle struts. Why they felt the need to go so overboard on that element with BOTH a 'spilt' in the center AND the 'swept back' look that's more akin to the ST:TMP 1701 Refit model is beyond me.
I could have accepted a straight 'split' nacelle strut OR a whole 'swept back' nacelle strut but for me, the combo of the two elements was just too much/going overboard just to be 'different' here.
And I find it annoying since I feel the NAILED their update/'modernized for 2019 cinema aesthetics' interior 1701 Ship's Bridge set.
But...that's me
[And sorry, I ranted a bit more than even I expected here]
