Is a degraded Teflon pan toxic to all of its users?
There is no current evidence that already-degraded PTFE (Teflon) poses any toxicity risks in its solid form.  To quote the University of California School of Public Health:


  There’s no evidence, however, that in­gesting any PTFE flakes that might have degraded from the pan’s surface over time poses any health risk, and the American Cancer Society notes that “Teflon itself is not suspected of causing cancer.” That makes sense, considering that PTFE is an inert substance, which means it doesn’t react with other chemicals.


Tibbs Bioscience says:


  PTFE is inert in its solid form, meaning it won’t react with other chemicals, which is what makes it such as great non-stick coating. As such, the minimal PTFE you would ingest will likely pass through the digestive tract without harm.


Other sources I checked had the same answer.  The fumes from overheating PTFE are known to be unhealthful; the solids left behind have no known issues.

Note that the same is not true of another chemical that used to be used in Teflon, PFOA.  Again, per Tibbs:


  After repeated heating and cooling, it is possible that the PFOA could migrate into the food. Research suggests that PFOA interferes with hormonal balances as well as reproduction and fetal development 


The problems with PFOA have caused manfucturers to stop using it in Teflon production.  However, if you have an older Teflon pan (pre-2013), it may still have PFOA, as might Teflon pans outside the US and EU.