The submitted headline misrepresents this post.
From the post:
“At present, it's not possible to make bootable copies of Big Sur, even with asr, Apple's own built-in replication utility. As such, we haven't released a Beta, or even an internal Alpha, because it wouldn't meet our own requirements.
So, for the moment, we're holding back, hoping that Apple will fix the issues [...]”
At our company we try to buy refurbished T2 free hardware only for this reason.
We'll probably jump ship if a great surface studio 3 comes out.
After almost 40 years of being a Mac Design shop...
We're just sad and want 2005 back.
Title correctly represents that hope as specious, and as all titles only need to depict the current reality, "at present" can always be elided.
I am not commenting on the likelihood of Apple to change this, or whether they should or should not.
I am only saying that the submitted headline misrepresents the post.
Lots of use cases become impossible without it
MacOS sand-boxing won't give the user write access to the System folder, anyways. Apple management might not see the point in a user booting externally, when they could move their User data to an external drive, instead.
If Apple walls off the ability to boot off an external drive, it's bad for 'power users', but good, in some ways, for Apple: stronger lock-in, tighter security, easier to sell higher-spec'd Macs (ie: with larger hdd's), and more iCloud subscriptions (cloud storage).
If the new macs do boot external drives, I would not be surprised if it's severely "nerfed" - I don't expect _any_ access to the onboard storage, for example (which would break all the use-cases you listed anyway).
"This build continues our beta testing cycle for macOS 'Big Sur' 11. In the current macOS beta, CCC will create Data Volume backups of any Big Sur startup volumes. Apple's APFS replication utility is not currently capable of replicating a Big Sur System volume (as of Big Sur Beta 6). We're working with Apple to develop the functionality within macOS that will allow third-party backup applications to continue making backups of macOS System volumes. In the meantime, we're making complete backups of your data, and those backups can be seamlessly used alongside the macOS Installer or Migration Assistant to produce a bootable backup or to facilitate a restore."
I‘d honestly be pretty surprised if Apple eliminated bootable backups. It’s just too important. The fact that it’s a power-user feature should not be a disqualifier. Lots of Apple users fall into that category, and I think Apple already has some work ahead of it to restore good faith with those folks.