Honestly before we even address that very valid concern, as somebody who regards Chaos Theory as the greatest stealth game ever made I think the larger concern is flat out just this remake even being a good goddamn stealth game
The fact of the matter is that when it comes to depth, stealth games have (for the most part) regressed mechanically since Chaos Theory over the last 19 years. In 5 years, Ubisoft went from the most dynamic light/dark and sound based detection systems ever created to binary "stick out like a sore thumb/invisible" and "nuclear explosion/completely silent" detection systems. Modern day Ubisoft is most certainly not 2005 Ubisoft. To say my faith in them to do the original SC trilogy justice is non existent doesn't even come close to describing the deep rooted frustration I've had at Ubisoft for 14 years because of them being the catalyst for my favourite gaming genre regressing ever since 2010.
Sam Fisher absolutely is not Sam Fisher without Michael Ironside, full agreement there. But even if they get him, this still won't be a true Splinter Cell unless Ubisoft actually put in the goddamn work to add the smallest sliver of depth to the gameplay. And seeing how AC Mirage turned out in comparison to what AC Unity (a game made literally a decade prior on inferior hardware) was like, I have absolutely no trust in Ubisoft to do this franchise justice and frankly wish they would just let it be so this remake doesn't potentially tarnish the legacy of the first four games more than Conviction and Blacklist already did.
This also operates on the assumption that modern day Ubisoft even has the organisational managment to not let this remake turn into vaporwave, which I'm not exactly ruling out either.