A slight adjustment. The PMTA for a newer product doesn't have to have been approved as of 9/9, but rather accepted for review.
"... if a product SKU is not covered by a PMTA that has been accepted for review by the FDA, or if a manufacturer has simply failed to file any PMTA, those products cannot continue to be legally sold after September 9, 2020...."
From other info it sounds like the overall review cycle may take a decent amount of time before all accepted for review items have determinations made.
"...Even if applications are submitted for only a portion of those products, the likelihood of FDA reviewing all of these applications during the one-year review period is low, given that this would be an unprecedented number of applications and several orders of magnitude greater than anything the Agency has experienced..."