Yes, it's going to cause a lot of confusion and missed meetings. At the moment everyone says "pacific time", but now that will mean two different things.

I think we'll need to say Vancouver time or California time.

Maybe people will finally learn the difference between PST and PDT.

They won't.

In my professional experience, having needed to work with relatively unsophisticated people across many time zones, the only thing that worked consistently was "[City] time".

That way people could always check 'what time is it in X now' or 'when it's X in [City], what time is it here', and get correct responses.

Descriptors like "Mountain time" are too vague, especially when there are various places that do/do not practice DST within that timezone, or there are similarly named time zones internationally. (Australia has Eastern and Central time too, for example, and in summer - which is northern hemisphere winter - they split into four different time zones due to varying DST practices.)

The worst by far is trying to be exact and specifying things like "EDT". At best, they're going to guess that that's Pacific time. At worst, they'll write down "EST" in their date books, because that's what they're used to, or "ET", or even "DST".

Mountain time is ambiguous due to Arizona, and yet we still use that phrase. Hawaii-Aleutian time is also ambiguous: the Aleutian islands do daylight savings, but Hawaii doesn't.

Casual speech doesn't use the city names (like America/Los_Angeles for pacific time); presumably we'd have Pacific time (America/Los_Angeles) and BC time (an update of the existing America/Vancouver). If Washington's time change ever gets approved it would presumably become simply Washington time (America/Seattle maybe?).