I don’t think there is really anything in the pipeline.
I think “plaid” is just Elon’s cheeky term for an over-spec’d motor for racing. Probably sacrificing longevity and reliability for a few extra kW.
The Raven motors are the latest and greatest, and will probably be around for a few years. The original motors have been around for a few years.
Having said that, Tesla is always improving things, so whenever you buy you can always find a reason to wish you’d waited. But then you’ll never get one!