My tech company relies heavily on custom drive letters. If this feature goes public, we will never move off of Windows 10. It would literally kill the business if we couldn't see which drive we were accessing.

I think most people have misunderstood these changes. Drive letters are not removed, but the option "Show drive letters" in folder options is removed. By default, that option is enabled, so the drive letters will be shown, now if you want to disable them you'll have to go to the registry.

Just like "Hide protected OS files" is enabled by default, it will remain like that, if you want to show them, you'll have to fiddle with the registry instead of just changing an option.

I cant remember where I saw it, but there was a long windows conference on youtube recently but they are planning a big windows revamp it might be part of that, This time its not just front end but a lot of backend stuff is changing. including trying to make Adminless users the default without losing any important functionally for the average user.

It doesn't sound like they're removing the displayed drive letters so much as removing the setting that lets you toggle them on or off.