Will the website "538" cease to exist by the end of 2025?

If the brand is retired but ABC continues to maintain a similar feature, this will still resolve Yes. The question regards whether or not there continues to exist a set of active web pages known as "538" or similar (eg, "538 politics", or an altered number reflecting a change in the number of votes in the electoral college), descended from the original website (ie, holding things like the original trademark). It does not need to retain the same URL to count as continuing to exist.

If the website is in archival mode, whereby the owner unambiguously does not intend to post any new content in the future, this will also resolve Yes. If the owner does not post any announcement of shutting it down, and it's possible that more content will be added, this will resolve No.

I will not bet on this market.