Thing about your comment is "Who would buy it" assumes it's basically the same and people are indifferent. My griping is assuming ARM is generally worse. But if we take this alternate world seriously then the reason for ARM is superior performance, so the answer to "who would buy it" and "why would developers switch" is driven by that - like when Apple was falling behind with PowerPC - it wouldn't be Microsoft pushing it on an unwanting market, it would be a demanding market pulling it with demand.
If Samsung could push a better-than-Intel chip, would Microsoft not want a piece of it?
If Samsung Chromebooks were suddenly more powerful than an Intel i7, would developers not sit up and take notice?
My contention is they can't, because ARM isn't that different, and it's Apple's black magic that is the real difference.
Apple is in a position where it can move swiftly and decisively. They have an army of software engineers who can port Apple's OS and associated Apps to a new architecture. They can force their entire ecosystem to move to a new architecture, and are emboldened by the fact that they've done it twice in the past (the first time they were more hesitant).
If Samsung wanted to pull down the latest Qualcomm ARM chip, slap a Macbook-sized heatsink on it, and go head-to-head with Wintel and Apple, they would fail. What are you gonna run? Linux? Some abortive version of Windows on ARM that doesn't support the vast number of x86 apps?
Even ChromeOS is missing barebones necessities like Photoshop, so professionals won't touch it. So the ChromeOS market is doomed (at present) to have "thin & light" and "long battery life" as it's only selling point.
I think we'll see M1-style ARM devices come out of the woodwork in 2021-2022, running ARM Windows and Linux and ChromeOS, simply to attempt to copy Apple. But I don't think they'll be as successful, simply because the apps aren't there, and no one can force developers to port to the new architecture as Apple can.