So, if the employer no longer exists, and the employer-sponsored health plan no longer exists, the right to buy in is meaningless.
As employees, people are seldom under the delusion that they work for, e.g., ADP. My last company paid me through a processor. My direct deposits showed as coming from the processor. To any bank, it looked as if I was employed by the processor, but the employees knew who the employer was. Should the employer suddenly cease to exist and owe employees anything, employees will go after the employer, not ADP.
No, not really. Do a search of "insurance claim denied" and see who is on the hook. Even in the case when the processor simply decides not to pay.
Employers usually pay at least half, so this doesn't change my 2x-4x range.