@lauren since there is SO MUCH incentive for the decisionmakers to make different decisions, I'd say there's plenty good reason to assume it's still an open question, even if that outcome might be likely.
All it would take would be for one national party organization--either one--to decide they'd like to hold the presidency next year.
If either party chooses a different candidate they bear a hugely increased chance of winning, and that's quite the reason they'd choose a different candidate.