Aging curves need to be factored into everything, but no teams should categorically trade guys once they hit some age threshold. Case by case basis.
The Red Sox are probably pretty happy they didn't get rid of Ortiz when he turned 33.
What specifically about EE makes you want him gone, or makes you think he's going to drop off? Much like Ortiz, he seems to combine a unique level of power, patience, and contact. Same with Jose. Of course they could fall off a cliff at any point, but graceful declines are more likely IMO.