I'm just gonna say this now, and you can quote me on this when it comes to pass.
After rewatching all of PapaGenos's Google Theory videos, I am hedging my bets on Google Theory. I believe it is 90% likely real based on several factors:
1. It is a common type a real leak. Ie, a slip up from a major corporation that does business with literally everybody. On par with retail leaks that usually turn out to be real.
2. It is severely unlikely that a troll bought Google ads hoping that a random person would notice a pattern, and no one has been able to pull the same off the sams "trolling".
3. The process to make the ads appear no longer works, and the blackouts (see the 2nd PapaGenos video) hint that Nintendo may have caught on and blacklisted the ads.
4. Banjo was confirmed, who was part of the Google Theory.
5. Out of all the names tried, "Hero" was not tried. But if we had a magic time machine, this likely would have all but confirmed the Google Theory.
6. Since Doom Slayer does not have an agreed upon title, and the name "Doom Slayer" had to be specific, "Hero" was likely the same way, which is why the Theory did not confirm Erdrick while it was active.
So, at this point, unless Vergeben speaks out against it, I am 90% sure that Google Theory is correct, which means that in my mind, Doom Slayer and Ryu Hayabusa are CONFIRMED.
Hear me now, quote me later.