I suspect that you are correct, in that as time goes on, we will hear much more about the possible biotic effects of shifting pCO2 on ocean alkalinity and shellfish, than about temperature or sea level rise.

On the other hand, it was only about 3 million years ago that atmospheric CO2 was at 400 ppm (our present level) all quite naturally, and I'm unaware that the paleontologists notice any mass extinctions among marine life at that time.

(Of course, at that time, equilibrium sea levels were probably 50 or 60 feet higher than they are now, and lots of us with coastal real estate {myself included} wouldn't like that ...)   :-/