It's time for Ponting to go!
I remember when Doug Walters came back for Australia in 1980/81 after last playing for Australia in 1977 (he missed the first season after WSC)
Dougie played 6 Tests and scored 397 runs @ 56.71 but at age 36 was dropped for the 1981 tour of England, with his poor record in England being stated as the reason (18T, 745 runs @ 25.68, HS 88, 6 fifties).
Well Ponting at age 38 will next have to play in India, where he record there is comparable to Walters in England (14T, 662 runs @ 26.48, HS 123, 1 century, 5 fifties).
With his current form of 166 runs @ 18.44
in his last 5 Tests, Perth has to be make or break for him.
Here are some other players dropped with their record for their last 6 tests
Dean Jones, 527 runs @ 52.70
Michael Slater, 307 runs @ 27,90
Mark Waugh, 249 runs @ 27.66
Kim Hughes. 176 runs @ 14.66
So Ponting is in Kim Hughes territory now and considering Hughes got a pair in his last Test, they are very close (Hughes had 176 runs @ 17.60 in 5 Tests preceding his last).
I say make the call now as Khawaja, Hughes & Watson are ready replacements and all are far better than Trevor Chappell who replaced Walters when he was axed