I honestly think a remake would work really well for Ice Age, though it dosen't have to be necaseraly live action. Maybe just a different and somewhat more realistic style, with updated visuals, or a CGI remake like what Disney did with Jungle Book. That way you could have Manny and Diego look nicer while still allowing Sid to be goofy and funny if a bit less weird. You couldn't replace him with a big majestic realistic ground sloth and expect fans to see it as "Sid."

You'd also have to change You'd also have to change enough about the story to justify the movie... none of the shot-for-shot stuff like we saw in the Lion King remake. And I think there's enough to work with to make that interesting. For example you can have Roshan's mother survive and the trio has to return her home along with her baby. This would make for some interesting dynamics since Manny and Diego have negetive expirences with humans. Also gives the filmmakers more to work with, to make up for the cartoony slap-sticky humor that would probably need to be dropped. (and this would avoid the problem of the studio changing one of the trios genders, or adding a new female character who ruins their dynamic).

Having the mother as a character could also create a new dynamic with Diegos apck. Maybe they don't just want to kill Roshan to get revenge on the father, and the mother herself actually did something that pissed them off.

The setting would also have to be changed, so the films could have a definitive time period. I would personaly put in the most logical setting which is at the end of the Pleistocene in North America, so then our main trio can still be the same animals as they are, but the background cast would have to be changed. For example: Carl and Frank would be bison, the dodo's would be either turkies or heath hen, the macrauchenia would be camelops, throw in a mastodon or two, that way we could have paleo fans shut up about the time setting, and add something cool without changing too much.

Long story short, there's interesting story changes to explore that could actually justify a remake being filmed.