I think Eric Bogosian is game to keep doing the show as long as it lasts (unless there's stuff we don't know about his personal life, which fair) but given his age, the show would be remiss not to have backup plans in mind for if EB ever does need to step back:
Daniel merely moves off-screen. This is very simple and effective and leaves a window for EB to cameo as able. The source material accommodates for this as well, unless they plan to do something else w Marius.
Daniel is body-swapped. This seems likely even, given Daniel always seemed like a stand-in for David Talbot. Musical chairs ensure where ultimately Lestat ends up in Gru's long lost twin brother while Daniel ends up in...Raglan, maybe a new actor altogether to bring some new blood into the show in case Justin Kirk has other projects that'd keep him from committing to a main cast role.
Daniel gets de-aged by Fareed's mad science to promote Luke to main cast. This may be controversial because Old Maniel is so beloved for various reasons, so many fans may prefer to see Daniel continue to be played by an older actor. But Luke's been with the show since S1, he has established chemistry with the cast, we know he can replicate EB's mannerisms as Molloy; logistically it makes a certain sense. In story? It'd have been earned, to say the least.
















