I don't think so, and it largely varies on what the role that specific character from the Disney world plays, I mean Phil not speaking in Olympus in KH3 had to do with partly due to Nagai's death and also he didn't play much a role when compared to his previous KH appearances for Olympus Coliseum. Even Japanese fans who grew up with Nagai's voice of Phil from the Japanese dub of the film and the KH games would feel awkward if they choose a different actor to voice him. Of course that's subjective and debatable as we had two different actors for Winnie the Pooh in the Japanese version of the KH games before they passed away with Mitsuaki Kanuka taking over in KH3: Shun Yashiro who voiced Pooh in the first KH (until his passing in 2003) and Sukekiyo Kameyama who voiced Pooh in KH2 and BBS (until his passing in 2013).I don't want to sound insensitive to Japanese culture, but is that silence of characters whose voice actors passed away rule something that they enforce forever? I can understand not recasting for a project that they were currently working on when they passed away, but would they still enforce it 10-20 years later if the property is revisited?
I think They only would replace an actor/actress if the character is important and if they pass away during production of an episode of a show for instance in the 2011 adaptation of Hunter x Hunter, Ichiro Nagai voiced Chairman Netero, but when he passed away Banjo Ginga took over the role starting in the final half of the Chimera Ant arc. For Bleach, Tomoko Kawakami who originally voiced Soi Fon passed away before Houko Kuwashima took over the character due to Soi Fon appearing in some episodes. Even the same can be said when the original voice for Professor Oak and the Narrator in Pokémon Unshō Ishizuka passed away they got a new actor, along with Bulma's original voice actress Hiromi Tsuru passing away before the got a new voice actress to voice her in the later episodes of DBS. Other times if the character doesn't play a big role or the voice for this character that the actor/actress played is so iconic to be replaced they would decide not to recast them out of respect for the actor/actress (e.g. Tomuki Dan as Kisame in Naruto).
Also it isn't in Japan, but also in some American productions like in The Simpsons and some Pixar films, when the actor/actress who voiced a particular character pass away they either would recast them or in the case with the Simpsons they "retire" that character out of respect for the original actor/actress.