At this point, most forecasters think it is probably 50-50. Polls this far in advance of the election mostly measure name recognition as folks do not begin focusing on choice until after both parties have selected their candidates.
Trump's big downside is that he: 1) narrowly won with a large number of lean Democrat voters either voting for third parties or staying home (and given the pre-election forecasts which had Clinton leading, they thought they could safely abstain or cast a protest vote); 2) even with no disasters having hit, he is historically highly unpopular. His big upside is that, today, candidate non-specific factors exist that usually result in a solid win by the incumbent. However, there is no guarantee for either side that conditions will change between now and the election in a way that favors them.