I have heard QANTAS now have TCAS on the MEL as a result of NAS - No TCAS, no trip. Don't know about others....
Not quite accurate.
TCAS is a MEL item I would guess on all aircraft, each aircraft having it's own Master MEL from the manufacturer, this can them be altered to an Operators MEL with approval of CASA.
For example Eastern OMEL for the Dash - TCAS 10 day item no operational restrictions.
Is now being changed to add conditions that the aircraft basically can't operate out of Class A with an inop TCAS. Still a 10 day item so theoretically could spend 10 days going SYD-CBR