Yeah, my objection was to the precision that your wording implied.
(realistically, I think the outcome of an unpatched fork is the collapse of bitcoin and people becoming very wary of anything claiming bitcoin in its genealogy (or even inviting close comparison to bitcoin))
No, accidental fork will be reverted and people will go on with the previously working software. Bitcoin can collapse only when it's non-recoverable (e.g. ECDSA or SHA256 is completely broken). If it is recoverable (like in all cases mentioned above), then there will be just a short period of turbulence.
(realistically, I think the outcome of an unpatched fork is the collapse of bitcoin and people becoming very wary of anything claiming bitcoin in its genealogy (or even inviting close comparison to bitcoin))