Can't say I'm particularly excited, here, but I'm also nearing 40 and am clearly not a target audience member for Disney any longer at this stage. My kid nephew will be thrilled that Cars will be represented, he loves the franchise, so I'll be happy for him the way I was happy that he enjoyed Runaway Railway, but "it's ok, whatever, the kids will love it" is the mentality that's moving the parks further away from being the top-level experiences they were once known for being.
Liberty Square and Frontierland were clearly designed with a pretty thorough aesthetic plan in mind: a slowly revealed timeline that goes from the eastern colonies pre-Revolutionary War, out to the Mississippi around the 1830s, the lodges of the Rockies in the 1870s, and then the red rocks of the far west. It was essential to the "theme" of the, y'know, theme park. Not everything was perfect, e.g. the Haunted Mansion isn't exactly set in colonial America/Splash Mountain was set in the American southeast but situated by the far west-inspired Thunder Mountain, but through a lot of effort, artistry, and a keen eye for detail, such inconsistencies became very easy to gloss over and the whole could become greater than the sum of its parts.
Now, things are changing; this isn't inherently bad. The park is buckling under the demands of crowds, it needs expansion, and, unfortunately, shareholders want things to happen so they can profit more by any means necessary. And changes could be made that might force you to somewhat upend this initial theming...but that doesn't mean it can't be done tactfully, or with an eye towards something fresh and new. Like, people saying "how about an area themed to natural beauty of the Pacific Northwest/Rockies"? That sounds wonderful!
...However, we know what's driving this (no pun intended), and it's not an interest in American landscapes or culture. It's the shareholders saying "you're sitting on (insert IP here), get it in there, build a ride, and sell some merch". This isn't about having fun with a period/setting of American history, it's about shoehorning a property in and, given the company's recent track record, doing so with no real regard for thematic consistency, aesthetics, or place setting. That's fine if all you care about is individual rides, but a huge part of Disney's allure has always been the parks' general ambiance and ability to transport people to times/places, but that's clearly not the goal any longer since you can't overtly monetize that.
At this stage, I'd rather they just tear the band aid off: if all we're ever getting anymore are rides based on movies, then just drop the idea of themed lands altogether, stop insulting our intelligence. EPCOT has nothing to do with EPCOT anymore; the new Animal Kingdom plans mostly walk away from, y'know, animals; and now the themed lands of Magic Kingdom won't really meant for their purposes anymore at this rate, either. If we were being realistic then a ton of this stuff would be going to dedicated areas of Hollywood Studios, which always felt like Disney's best option for making its own Islands of Adventure-style park based around IP, but the current business plan is about immediate profits, not about long term quality and care.
As for all the political wrangling going on in this thread; look, I'm a US history teacher, so it's rich to hear from some people saying something like "paving over the river is rewriting American history because something-something woke blah blah blah". To borrow a phrase that's been popular lately, such ramblings make these people seem, well, weird. The easiest answer is the one that's been in front of us all along: it's money, Disney wants more of it, and the only idea they have now for making is "keep copying Potter, we'll get it right, eventually." If the concern was really things being "problematic", they could still be producing all kind of original western-themed attractions and avoid just about anything "problematic" in the process, but they aren't doing that because they've become creatively bankrupt, not because they're driving a political agenda you've talked up in your mind to trigger yourself.