The play here is simple: buy 500px and rebrand it as “the new Flickr”. Migrate the entire existing Flickr user base and instantly make them all happy.
Yahoo buys DuckDuckGo and starts serving ads on it, and make it the default Yahoo search engine. Yahoo is already an option on most browsers and devices (like iOS) so the potential user base is there. Putting the Yahoo brand behind the DuckDuckGo power, might be a win-win for both.
This is an excellent, viable plan to revive Yahoo!.