When the 538 first launches its flagship model for predicting the the winner of the 2024 US Presidential Election, this market resolves to the name of the person the model currently projects to be the most likely to win.

If 538 has multiple models, this resolves based on whichever model they present as the "main" model. In 2020 there was only one version of the model, but in 2016 there was "poll-plus", "polls-only", and "now-cast". Polls-only was the "main model", in that case.

If there is no such model in 2024, this resolves to "other". The model launched on Jun 29th in 2016, and August 12th in 2020. But perhaps it will be earlier this year, given that we likely know who the candidates are already.