It's interesting to consider the OG cast and crew these days.

[Sensitive] Joss Wheden: SJW/male feminist who was outed as the creep they always are after cheating on his white during the filming of Buffy with the young actresses he always wrote to be barefoot because he's also a footfag.

Shepard Book: Dead.

Jane: Literally coined "Gamergate". Was in Chuck as an all-blooded American caricature.

River: Waiver thin mint girl who was ironically compared to 'an albatross' in Serenity then went on to be just that in every other show she went on to be part of: The 4400, Alphas, Sarah Conner Chronicles. Summer Glau was a sure sign a show was getting cancelled if she suddenly showed up on it.

Inara: "Jumped on the Stargate gravy train" as I remember someone once describing her. She was only really in the latter half of the 10th season but ended up a very significant character and one of the final antagonists for SG-1. Was also in Homeland or a similar show regarding national security.

Kaley: Also "jumped on the Stargate gravy train" after a brief cameo as a human-wraith hybrid when she was cast in the recurring role of Stargate Atlantis' chief medical officer after they killed off the OG one.

Zoe: Hasn't really been in anything that stood out? Much like most of the cast there's a lot of VA work but out of the lot Gina Torres is probably the one I've seen "in person" the least. Apart from her work as Superwoman in one of the Justice League animated movies and some other VA work I've not really encountered her much.

Wash: Wacky fun. Perhaps one of the most successful out of the group and very often a remarkably versatile actor who can do an impressive range of roles. His role in Dollhouse [another Whedon show] alone showed how well Tudyk can fool audiences with his acting. Also honourable mention as "Steve the Pirate" from Dodgeball. Yarr.

Simon: Showed up in Arrow as part of the CW version of the Suicide Squad, was the one that tried doing a runner and got his head exploded for it. Later literally came out as gay and bitched about things as is the standard practice now.

Mal: Castle. Which ended up a giant clusterfuck after Stana and Nathan fell out. The Rookie, a show I managed until the first episode of the second season when Nolan's superior was recast/replaced because the original stronk, black woman was fired after making false accusations against one of the side characters, also played by a black guy. The new one literally shows up, takes out a full automatic rifle, and fires it [til it clicks] at a group of gang bangers. Not only was this picked apart because the rifle she used doesn't work like that, but it in no sane world would be a move anyone could make without being fired so fast they would feel the Doppler Effect.

So while modern remakes/reboots/whatever quite often cast legacy actors in to the show in some form I can't see that working too well this time.

There is no way in hell SJWs will let the "hwite male" who coined 'Gamergate' anywhere near the show and in most "discussion" they side with Stana vs Nathan regarding the fallout from Castle. Whedon doesn't even need considered, he's easily persona non grata after his dirty launder was aired along with his atrocious writing for Avengers: Age of Ultron.

At this point I'm just going off on a tangent so everything from here on can be skipped relative to Firefly.

Smallville was legendary for guest stars from both legacy media as well as connected characters.

1. Christopher Reeve appeared as a wheelchair bound scientist who was searching for Kal El.

2. Margot Kidder was cast as the assistant to Reeve's character. Both are now dead, Reeve understandably so after his paralysing accident left him in a condition he wouldn't last very long anyway and Kidder committed suicide in 2018 by overdose.

3. Additional movie castings also included Helen Slater as Lara, Kal El's biological mother. Marc McClure, the original Jimmy Olsen, played Dax Ur at one point. Terrence Stamp who played Zod in Superman II was the voice of Jor El throughout the show, although the character was played by several different actors including Julian Sands at one point for his original mortal body back on Krypton.

4. Clark's human father in Smallville, Johnathan Kent, was played by John Schneider who played 'Bo Duke' in "The Dukes of Hazard" (1979-1985). In one particular episode Tom Wopat guest stars as one of John's oldest friends. Wopat played the part of Luke Duke next to Schneider for the run of The Dukes of Hazard.

5. Linda Carter played Chloe's mother.

6. Teri Hatcher played Lois' deceased mother, appearing in a video tape she had left for her daughter.

7. Dean Cain appeared in a one off episode and was for all intents and purposes Vandal Savage, playing an immortal who could be "killed" just not permanently. It was one of those moments during the episode something was abundantly special about Cain's character as within moments of threatening Lex and Chloe the response by Lex was to pull a handgun and empty it into Cain's character. A high profile casting like a former Superman experiencing such an extreme event just screamed foul play and rightly enough it turned out the bullets didn't properly kill him.

As a side point high profile casting like this can often give away a new character has significance. When Ramsey Snow first appeared as "Reek" in Game of Thrones anyone that had seen the UK show 'Misfits' would have instantly recognised him as 'Simon' heavily suggesting he was playing a far more important role even without knowing what the truth about Reek was in the books.