Grow the f up.
No, it isn’t disrespectful to the previous actor for a new actor to play the character. I’d rather new actors than cgi.
It especially shouldn’t be a problem if the new work is a remake. I can see being taken aback by a character being recast within the same series, but a remake is a clean slate with a new cast. Enough with the attitude that nobody should ever play a certain character again.
Do you know that before we recorded stuff, we had centuries of actors exclusively acting on stage? And yeah, plays had and still have new casts of actors play roles that were previously played by other actors. This is normal.
Actors aren’t getting younger.
However, I would prefer the new cast of a series to look very alike the old cast, so one could better picture the role as a person, instead of like James Bond as an abstract British concept of recklessness in a tuxedo.