Sachin (36) is probably biting his nails now but he need not worry about his record at the moment despite Ponting (34) being 1.5 years younger than him
Australian selectors are known to be more ruthless than other boards with guys like Merv Hughes in the selection committee. One or two bad series with the bat and pressure may be put on Ponting to quit or-else...
Sachin on the otherhand can rest assured that even if he picks and chooses series from now on or has a lean patch with the bat, the BCCI and people like Gavasakar w'd back him to the hilt just so the record stays in India :)
You are assuming too many things Asif. If sachin can be replaceable, he will be. I dont see a good replacement for Sachin and Dravid in test in near future.