As the aircraft is now assumed to follow designated waypoints as it flew NW it is likely that it was in LNAV.
If the assumption now is that the aircraft flew at cruise altitude and normal speed it follows that there could be 2 endurance times and distances
1 Pack on
2 Pack off. With the bleeds or packs off the endurance would be extended due to better fuel economy.
How does this tie in with the final ping timewise (which equates to empty tanks). On that basis it should be possible to draw a series of circles from the last probable waypoints; MEKAR IGREX or the FIR at 92E into the southern Indian Ocean.