Speculation on the Human threat in Godzilla vs Kong is.

We all think it's going to be Destroya or Mechagodzilla is what we humans are going to throw at the titans. However, given that Toho's Licencing of its kaiju was/is/maybe expiring after this film I think we will be threatening the titans with something else the first/second Antigodzilla-superweapon of the Heisei era: ANEB Anti-Nuclear Energy Bacteria. This would only kill off those titans that feed on radiation to survive. this would make Kong and the other creatures on skull island immune to the bacteria. as we see kong eat a meal of giant squid sushi and the Skull crawlers eat several humans and animals on the island as well.

so eather way we would still have the Monsterverse...

The question is who would it be that creates the ANEB well it's likely the US military who likely has genetic samples of The titanus Jinshin-Mushi species and their parasitic nature as they feed off the stored atomic energy of the Gojira titanus species. They will use this to create a bacteria that saps the atomic energy from the sells of the atomic titan species aside from the MUTO/MUAO( massive unidentified airborne organism which is how I think of the male of the species) who would be immune to it do to them being original legendary creations.

It's very likely the ANEB will be tested on Kong as let's face it skull island is the perfect place to test something like a bacteriological weapon system. given that kong does not seem to be a titan who lives on atomic energy as we see him eating the aforementioned squid it's likely the bacteria will mutate kong well also making him sick and violent. his cries call the titans to the island.

who would give the ok to test the ANEB, Senator Williams( who was played by CCH Pounder in GKOM) who is now president Williams (2020 is an election year) and use her executive powers to ok the test. 

Monarch meanwhile will learn about it from the camera's on skull island and that the bacteria is stored on the island and will create a virus designed to target and infect the ANEB to render harmless to save the titans who get infected by the bacteria from fighting the enraged kong.

Godzilla and Kong face off as an upgraded argo race to skull island using the chaos of titan warfare to infiltrate the storage area of the ANEB

step one of the plan is to infect the ANEB with a virus to render it harmless.

back on skull island, Godzilla arrives to face kong and save his subjects.

Monarch manages to erase the data on the ANEB and the G team successfully deploys the ANEBV (anti-nuclear energy bacteria virus) to the infected titans. however, something happens to the osprey that was carrying the incendiary weapon need to destroy the stockpile G team is go with plan B infect the stockpile with the ANEBV. However the stockpiled ANEB had mutated and the virus turns the massive stockpile into something else thus Hedora, Destroya, or a new monster is born. Godzilla and kong must face off against this new threat. Godzilla and kong survive however the new threat had the Jinshin-Mushi's sonic roar and managed to shatter Godzilla's dorsal plates.

The cave painting is seen shows two murals this time one of kong facing a monster with hooks for hands the other a painting of Godzilla facing a humanoid rose.

Post credit scene: we see Charles talking on his phone well waiting for his computer to turn on. "so you finished project space hunter as well. the program finished downloading now. goodbye" and hangs up the phone.

the screen has several icons on it however we can only see three the first one is a rose, the second a ruby, and the third a simple blue piece of paper. He clicks on the rose and the screen changes: Project rose 

DNA of a rose, Titanus Gojira and Lindy Jonah. we see a rose with teeth in the center of the bloom. he then clicks back and clicks on the ruby we see a mummified monster with the heading "project: space hunter" it also shows that the creature has a heartbeat

he goes back and clicks the final icon however we can make out the icon next to it which is the greek letters P and N. the icon opens up to showing: project Bagan under it are just for words: Ghidorah DNA sequencing Compleat. the screen cut to jonah smiling before cutting to the warner brothers logo.