They have released a host for the Mole and it is NOT Grant so I don't think this really affects whether or not TAR AUS will return. I personally think it will though maybe not till the second half of the year - There is no way 7 will dump a show that has done really well rating wise.
It hasn't rated the best but that was due to poor timeslots (especially in S2). 7 should give it at least one more chance.
TAR24 - YouTube, Dave & Connor, Afganimals
Survivor Cagayan - Sarah,Tony (#goodcopbadcop alliance), Spencer
MKR5 - Twins (who aren't Twinnies), Carly & Tresne, Surfer Dads, Pun-man & Shannelle
BBCan - Kenny, Paul,