And the band plays Waltzing Matilda
And the old men still answer the call
But year after year, their numbers get fewer
Someday, no one will march there at all

Waltzing Matilda, Waltzing Matilda
Who'll come a-Waltzing Matilda with me?
And their ghosts may be heard as they march by the billabong
So who'll come a-Waltzing Matilda with me?

According to Wikipedia there is only one Australian veteran of the Great War remaining, albeit three such veterans residing in Australia.

Altogether there are only 18 left with connections to that war and only 14 who have been confirmed to actively participate in the conflict

Lest they be forgot...