Just thinking about this.
Although the in-house production style continued through the seventies , and much product resulted for existing acts, no new successes broke through from this process, except for Thelma Houston [[new in the sense that she finally conquered the charts, became a recognized name , and thus became a formidable player in the performance circuit.)

I can't think of another "new" act that emerged after her , and perhaps the J5 were the last before her to arise due to the old school gang of writers and producers hanging out in the halls of Motown??

The rest broke through by their own musical talents and skills....Commodores , Rick James, Switch ....Lionel

Or am I over looking others??