The murals at Disneyland's Tomorrowland were ceramic tile murals. The only way to remove those tiles would have been to pry them off, shattering them in the process. Knowing that such an act of *desecration* (Walt would have called it getting rid of something old and irrelevant to make way for something new and exciting) would spark a hateful, fever-pitched furor among many DL APers, the folks at WDI tried to preserve the original tiles while presenting new well-themed murals. Yes, the way they chose to attach the new murals caused some damage to the tiles, but it didn't destroy them. [History is very important in this company, but simply being old does not make something sacred or unremovable. Sadly, many *faithful fans* have lost sight of that concept, which I'm sure would dismay Walt, since one of the ideas that really attracted him to creating a theme park was that every element of it could be changed without anything but imagination as the limit... I digress...]
The Seas Mural is not made of ceramic tiles and (like pretty much everything at WDW) was not intended to last forever. If the new exterior design calls for an identical mural, and they are removing rotten or damaged pieces, when it is finished you will not be able to tell. If the new exterior design includes a mural that has a different appearance, that mural will serve the purposes of the new story and it won't matter what was there before or what is underneath or behind (it's a facade, after all). Either way, the fact that there are holes in a wall on a building that is under construction is really not that big of a deal. Aren't there more pressing matters? If you want to focus on changes around WDW, why not look at something that is completed, adds to the story being told, and is pretty neat... For instance the cannons that recently appeared on the hill between Mme Leota's cart and the Haunted Mansion. Pretty cool if you ask me.