I wonder who they'll get to play Perry White?
I hope they remember that this is later in Superman's life, so they could cast an older actor. They went a bit young with Lois, so hopefully that won't set a pattern.
Really, this should be different from your standard Superman ensemble, because Clark & Lois are already a couple with a son, Jimmy and Cat have both long since moved on, and Perry's probably close to retirement age by now. And we've had a version of Maggie Sawyer already, and Inspector Henderson's on a different Earth. And the Cadmus characters are out because Cadmus is evil in this universe. So they would need to build a supporting cast from other characters. You mentioned Lombard, Troupe, and Irons. I don't know about Emil Hamilton, since we already had a gender-swapped Amelia Hamilton as a DEO doctor in
Supergirl season 1 (though maybe they're siblings?). Hmm... Maybe Bibbo? Dan Turpin?
But there's a lack of female characters here. Lana Lang could be included; surprisingly, she's never yet been referenced in the Arrowverse. Chloe Sullivan's a possibility (and has been established to exist on Earth-38), though maybe she's too associated with the scandals around Allison Mack. If John Henry Irons is on board, Natasha Irons could come with him. How about Kristin Wells, Elliot S! Maggin's Superwoman from the future (and a descendant of Jimmy Olsen)? Or -- ooh, how about Lori Lemaris?
There's also kind of a villain problem, since so many of the big Superman villains have been used as Supergirl foes that had no history with Superman. Maybe Lex will be a regular? But that still leaves a lot of openings for other baddies.