Don't believe anything a politician says. Abbott quoted as saying on 16/4/15 that NG wont be fiddled with. I would agree it would be political death approaching an election with that. The ALP would head into the election saying they will restore NG and the libs are GONE......
Fine print to his "promise" is that after an election he holds a mandate to govern (plebiscite was Howards term) and will blame the ALP debt for the need to balance the budget. He will then can NG / CGT benefits etc on some rentals. Bookies wouldn't take bets on this as its so certain (except winning the election !)