On the topic of FCG potentially being reincarnated--it makes sense as an option the party might organically consider attempting, but, as we saw with Laudna's death (and even Percy's way back when), input from the player is a really operative aspect of whether a character will be resurrected. Marisha clearly did not want to let Laudna go, so they pursued a long road to bring her back. Alternatively, Taliesin was totally willing to let Percy go if he thought the ritual offerings wouldn't be enough (shoutout to Vex's nat 20 persuasion check for this one).

And Sam? Well, Sam, as a player, loves to fail. Because failing is interesting, usually far more interesting than succeeding. We're talking about a guy who openly derides luck points and fervently refused to use the halfling luck feature except in the ONE instance where succeeding the roll would have had a worse outcome than failing. Regardless of how I or anyone else feels about losing FCG and/or wanting them back, Sam does not strike me as the kind of player who would want to bring FCG back after going out like this, available reincarnation or not. I would both suspect and anticipate that this will be FCG's final showing, just based on what I know of Sam as a player