I'd still say this was a winnable fight for Canelo. Makabu is on the smallish side for a CW and looked horribly slow and crude in his last fight against the smaller Mchunu (who's around Canelo's size) who had a strong argument for winning, so it's not like there isn't a possible blueprint here.
I think there's a reason Makabu was selected as a potential due to not being that tall at the weight and far from elite. Gingers gas tank was very poor last time out so I can't see that improving moving up another division. Majabu isn't great as a belt holder as he was clocked by Bellew in 3 so easily the weakest champ at Cruiser. The fact is Canelo needs to train for endurance rather than be too thick built for power. There's two reasons firstly as mentioned the gas tank is crap and his tendancy to fight in short spurts will simply be worse. Secondly although he cracked a compromised Krusher I'm not convinced his power will translate at the heavier weights with healthy prime guys as witnessed against Bivol. So his only chance is Makabu and that depends whether Majabu comes to fight or folds like a deck chair in the chosen round.