I think Mr. Turnbull could win a Labor seat if he was endorsed, however , Australia deserves a strong opposition, the best we can get, and Mr. Turnbull would be a superb leader of the opposition.
I think the lib plan would be to keep the caretaker opp leader for as long as possible, to deflect the flak. Possibly mid June before senate changes , or a couple of months pre next election.
Looking at opposition benches , they are just Howard govt clones , nothing new , no policies, originators of about 6 new taxes , and the biggest of them all .. the GST.