Nope. Not necessary. It's not like "back in the day" when so much was done by hand. Changeover at this point is primarily a software exercise and they will likely already be running pre-production test vehicles simultaneously with current platform vehicles shortly before they stop making "WK2" and start making WL officially.How long will it take them to gut the plant and retool, probably at least 6 months, so my guess would be they will stop making the current WK2 in June and start up in Jan 2021 with the new WL.
And more importantly, they'd run out of JGCs very quickly if there was a long shutdown because unlike most vehicles, pretty much every JGC coming off the line is sold to either an end customer or to a dealer. They are not force fed like other brands. Right now, something like about 1000 vehicles a day come off the line at JNAP with about 80% JGC and 20% Durango. That keeps up with demand. Shutting down early wouldn't fly very well. Don't forget that there's a second plant attached to the same property coming online, too, and while it seems that's primarily aimed at the three row, it could possibly play a role overall, too. Computers and robots are smart.