Like it or not if he gets the role he WILL be compared to Heath's Joker. As for heath he it felt like he got the joker character down PERFECTLY. All the details, the mannerisms it felt like he captured the true nature of the joker when others before him (including Nicholson) had not. Thats the difference here. I don't think it's impossible to match what Heath did but the script has to be on point as well as Leguizamo. If they give him weak material or try to make the next joker less dark then there's no chance
only two people played Joker in movie form other than Heath Ledger and one of them is from the 60's. Yeah people are gonna compare anybody who plays Joker to Heath, thats without doubt, but to say no one else can be Joker ever is almost retarded. All 3 movies that had Joker, are definitely entirely different movies too, so of course the character is going to be portrayed different in all of them. What made the Heath version so good was the fact that, he completely fit the universe of Nolan's work. He wasnt a slapstick version, or even that comedic (in my opinion more of a sinister comedy to him,) that, along with Heath's acting, made it so brilliant.
But i definitely agree that the script has to be great in order for it to work for any one who takes that role as well, and thats where i feel the judgement should be centered for now. Maybe they wont be able to duplicate the believability as well for the next joker and thats where it will fall apart. But we shall see.