Yeah they're pretty spectacular, people will lynch you if you cut down a baobab, literally. Its the embelem of the Limpopo province Basically every one metre circumference is 300 years and there are trees with 25-30 metre circumference trunks....
It would be like dying of old age, things stop working and funtioning. But theres probably a certain time when the plant is just dead, when it stops sucking up water probably.