This NYTimes article speculates that Donald Trump may be ineligible to run for elected office due to his role in the Jan 6 insurrection. Stephen Calebresi is quoted: "Trump is ineligible to be on the ballot, and each of the 50 state secretaries of state has an obligation to print ballots without his name on them."
From the linked paper:
"Section Three of the Fourteenth Amendment forbids holding office by former office holders who then participate in insurrection or rebellion....in particular, it disqualifies former President Donald Trump, and potentially many others, because of their participation in the attempted overthrow of the 2020 presidential election."
This resolves positive if any US state's ballots used on election day do not list Trump, and this is due to the 14th amendment or other issue related to the various legal charges against him. If Trump drops out of the race and he or his official representative explicitly, publicly, and unambiguously state that this is because he wouldn't be able to appear on the ballot in at least one state, this will also resolve yes.
The resolves negative if Trump is listed on every state's ballot issued on election day.
This resolves N/A if Trump is not listed for other reasons (eg: he is not nominated).
[The Colorado Supreme Court has ruled that Trump cannot be listed on the State's ballot](https://www.bbc.co.uk/news/world-us-canada-67768873?at_campaign_type=owned&at_bbc_team=editorial&at_medium=social&at_link_type=web_link&at_campaign=Social_Flow&at_link_id=40961B1C-9EC7-11EE-9205-EB53AAF30DC0&at_format=link&at_link_origin=BBCBreaking&at_ptr_name=twitter). Unless this ruling is overturned, this will resolve positively.