An answer will resolve YES if it ceases services (akin to Cohost in 2024), OR if the business is sold to a new owner (akin to Twitter in 2022). A sale has to be a full sale of the business - it can't just be "someone new gets a majority stake" or "ceo pushed out" or something like that. If the website has an unplanned, unannounced, complete outage for longer than 2 months, we'll assume it's shut down and resolve YES unless there's direct evidence otherwise.
Things that will not get a YES:
IPO
Company going private (without also being sold to new owner)
Ceo being ousted by board, majority stake shifting hands, or some other internal power struggle
Name change or rebranding (unless caused by purchase)
Specific features being removed
If all else fails, in the event that any result becomes too complex and the resolution criteria are inadequate to resolve, a manifold poll with the question "Has <company> been sold or shut down?" with the answers "Yes / No / Neutral" can be used instead.