Isn't the IRFU budget based on finishing minimum 3rd in the Six Nations each year? In which case I don't think Farrell has time to start major experiments with new players.
Much as it saddens me to say as a Connacht supporter, O'Halloran isn't at the level that test rugby demands (at the level we aspire to). He's also 29 in February.
If we do get beaten soundly in quarters, and on top of Japan i think Farrell is under serious pressure. He has been given much more responsibility since the announcement. He's not just a defence coach anymore.
My choice would have been don't announce the next coach and wait till the dust settle for the new appointment.
I think a poor World Cup will damage Irish rugby regardless and finishing third is the least of our concerns. A poor world cup is a defeat to Japan, poor v Russia and 13 plus defeat to the All Blacks (whom we clearly didn't want to face)