Does a revision launch count? Sights would have been set for a close to record performance (this gen) with how strong the software momentum would be in September, launch of the Lite model could push it over the edge.
Oh that revision will do something.
It actually kind of depends if Switch sales start to drop faster than expected between now and launch. If they do, Switch Lite can open to fantastic numbers and September sees a massive boost.
If Switch appears to hold between now and launch, it's possible Switch Lite launches lower than some would anticipate, but then it heavily makes up for it in the holidays. This would result in a lower than expected September, but better November and December sales.
Right now, my gut feeling is mixed. If people also treat the Switch Lite as a $100 price cut, then September could just well break the PS4 record. If there is some hesitation on it being handheld only, then overall sales could just miss it. It being late September also limits what it can sell in September. October will see a massive increase thanks to this.
Exciting times right now, and there is still a Pro version to be announced. If that launches in September, then yeah, Switch most likely breaks 500K going on 600K.