Graduate school is so specific. I'm not sure how it works in your family, but a graduate degree comes with no parental financial assistance at Casa de Fenwaysouth. The money tree has been harvested to its full extent, and is retiring soon. Essentially this is your son's chosen profession if he decides to go to grad school. In my mind, matching your son's chosen profession to the graduate school is a 100% weight...baseball is an afterthought since he is not pursuing a career in baseball. Undergrad, the weighting decision between academics and athletics can be "squishy" depending on what someone wants to get out of their 4 undergrad years. In the context of graduate school, baseball is a "nice to have" not a "got to have". If your son can somehow find a great graduate school program in his chosen field and continue his love for college baseball, more power to him. Certainly there will be programs looking for experienced talent.
JMO. Best of luck!
PS...To answer your question...no. We did not have this grad school conversation with our oldest son. He had a job lined up before his senior year started (economy was good), and he did not want to go back immediately after 4 years of engineering undergrad. He was absolutely ready for something different. A 40-50 hour work week in the real world was a joke to him, but he needed a couple years off.