I would assume that the songs are designed as hints about launch title 3rd party marketing deals, rather than 3rd party exclusives, with the main exception being Killer Instinct. The first one would presumably be a hint that MS has AC Ragnarok marketing. 2nd one would be WB's Superman game. 3rd one would presumably be a zombie game; Dead Rising is dead, so maybe marketing on a revived cross-gen version of Dead Island 2 from Sumo, which has been in development for several years now.
That being said, if those are what he is hinting at, it seems fake. Sony is rumored to have AC Ragnarok marketing with a reveal at Sony's PS5 reveal event next month. A new KI on launch was recently shot down by an Iron Galaxy dev I thought. I thought the Superman game was confirmed dead after multiple failed prototypes over the course of this gen; not even sure which WB studio would be developing it if it does still exist, Rocksteady is confirmed to be working on a new IP I'm pretty sure, WB Montreal is doing the new Batman Arkham, Avalanche Software is supposedly working on the AAA Harry Potter RPG, Monolith is presumably working on a new LOTR game even though the Middle Earth series is over now, NeatherRealm is a fighting game studio, TT does Lego games, WB Boston and Portkey are mobile studios.
If somebody's trying to hint at marketing deals, as to the reason for their hype....well then I hereby submit that this person isn't worth listening to in the first place. MS getting the marketing rights for something or other isn't going to enhance my enjoyment of those games.