Garrett Wang confirmed that Harry Kim was going to be in the Admiral Shelby role.
trekmovie.com
Considering what happened to Shelby, maybe it was not a bad thing that Harry Kim did not appear in the season. To appear promoted as captain, only to be unceremoniously killed off moments later, would not have been received well by the fanbase. Though it would have been in line with the ‘Harry Kim must suffer’ trope.
Your thoughts, TBBS?

Interview: Garrett Wang On The Joy Of Harry Kims In ‘Lower Decks,’ And Anger Being Written Out Of ‘Picard’
The 'Star Trek: Voyager' actor returned to the franchise for the penultimate episode of 'Lower Decks.'

As I understand it, the original plan was that Captain Kim was going to be kind of like Admiral Shelby [Elizabeth Deneny], that was going to be you.
Correct.
So, I was wondering how far down the road did they go with you on that?
It went all the way to my manager saying, “You’ve been cast.” It was originally a three episode arc, which then changed to two, then then changed to one. But I was told by my manager that I needed to be in the LA area in January for a fitting for Picard. So it was there. It had progressed fairly far actually having Harry on that show, pretty darn far. The script was written. Harry’s name was in there… Jeri Ryan said to me, “It’s so funny because we got sent a script, and Harry was in there, and all sudden, the revisions, Harry wasn’t in there.” I was like, “Oh, wow.” So, it went pretty darn far. And I’ll be perfectly honest, being a sci-fi fan, I was depressed for months after that when it didn’t happen. I was literally crying into my own sleeve. [laughs]
Considering what happened to Shelby, maybe it was not a bad thing that Harry Kim did not appear in the season. To appear promoted as captain, only to be unceremoniously killed off moments later, would not have been received well by the fanbase. Though it would have been in line with the ‘Harry Kim must suffer’ trope.
Your thoughts, TBBS?