Of course he has a chance at the Presidency, and anyone who legally qualifies does to an extent. Democracy isn't a precise science, so we can't empirically establish who is going to win the election next year. It could be George Pataki for all we know (although that significantly less likely).
Right now the GOP have a crowded field and there's still a long way to go. But any of the serious contenders could end up in the White House, including Mr Trump. Just depends how the votes go and how the states fall. Let's also remember Mr Trump is still leading, which gives him an even better shot then most of the GOP contenders right now.
Meanwhile I'll be preparing my bunker for a Trump presidency... better safe than sorry!