when Daylight Savings Time kicks in on March 8th (in the US) Cozumel will not follow, putting them an hour behind EST...So if they stick to this plan, they'll line up with EST (in the US) from November to March, and CST (in the US)from March to November.
No. Under the new plan, Cozumel will ALWAYS match US Eastern Standard Time (EST).
When the US moves to Daylight Saving Time, the east coast will be on Eastern Daylight Time (E
DT), an hour ahead of EST, and Cozumel will remain on E
ST. That will definitely not put it an hour behind EST, but it will put it an hour behind EDT.
Keep in mind that for many years Cozumel's time zone has not fully matched any US time zone because Daylight Saving changes were on different dates. Now it's a bigger mismatch.
when EST goes to DST it isn't EST anymore is it? It is then EDT. So when EST goes to EDT, then Coz time stays on EST, which is also CDT, but never CST, Coz is STILL EST?
That's the way I read it.
My view is that thinking of this as "EST" is wrong anyway. Think of it as Quintana Roo Time, "QRT". Sometimes QRT will match up with a US or other time zone and other times it'll match up with different ones.
My personal prediction is that this will quickly drive everyone up the wall and that eventually they'll either follow Mexican time zone conventions and always remain an hour ahead of Yucatán or they'll adopt US conventions and switch to Daylight Saving time with the US east coast.