WARNING: Spoilers for Ant-Man & The Wasp.
The ending of Avengers: Infinity War infamously saw Thanos collecting all six Infinity Stones and wiping away half of all life in the universe - including many of our favorite heroes. Such a bleak ending only raised further questions, like how can the surviving heroes bring back their friends, and everybody else? It is, of course, a question of "how" and not "when", considering some of the dust-piles, namely Spider-Man and the Guardians of the Galaxy, already have sequels booked in for the next few years, one of which is already filming.
After Avengers: Infinity War, all curious eyes immediately turned to the next Marvel Studios installment: Ant-Man & The Wasp, especially considering neither character was anywhere to be found during the events of Infinity War. And that paid off. Ant-Man and the Wasp was expected to take place entirely before Infinity War, but in actuality, the two movies take place in extreme timeline proximity, with the mid and post-credits scenes actually happening during (and after) the events of the massive team-up.
Ant-Man is Lost in the Quantum Realm Ahead Of Avengers 4
The Ant-Man & The Wasp's mid-credits scene finds Scott Lang planning a trip into the Quantum Realm in order to find some MacGuffin-energy to help foe-turned-ally Ghost. Aided by Hank Pym, Hank's newly-returned wife, Janet Van Dyne, and daughter, Hope, operating as his anchor to the real world, Scott launches through the Quantum Tunnel and begins his mission.
Unluckily for our snarky hero, he's slap-bang in the middle in the of the Quantum Realm when Thanos snaps his fingers, resulting in Hank, Janet and Hope being reduced to dust. This means he's now separated from his means of returning to Earth - not to mention stricken with what is likely to be an inordinate amount of panic and fear concerning the safety of his girlfriend and future in-laws.
This provides a direct link to Avengers 4. We know via set photos that Scott Lang has a part to play in the next team-up. Further, considering that Tony Stark is sporting some grey hairs in those set photos - whilst Scott Lang isn't - it can be further inferred that time travel will play a part in Ant-Man's future. Avengers 4 is, in part, a time travel film, and with Janet van Dyne's mention of "time vortexes", the post-credits scene may have provided a clue to how that will work too.
Ant-Man & The Wasp's End-Credits Finally Reveals Life Post-Snap
Avengers: Infinity War's end-credits scene saw Nick Fury and Maria Hill driving through some nondescript U.S. city when Thanos' apocalyptic finger snap begins to work its ill effects. Sirens are blaring, cars are crashing, helicopters tumble out of the skies, as people, animals and plants turn to dust everywhere. It's sheer chaos.
The next chronological post-credits stinger fans are given comes from Ant-Man & The Wasp; and the chaos witnessed by Nick Fury on the streets of Anywhere, USA seems to have abated outside Scott Lang's apartment window. After all, Lang still lives in a busy metropolitan area (San Francisco), but there are no sirens to be heard, no screaming, yelling or signs of panic. It can be extrapolated from this small clue that this scene takes place an indeterminate amount of time post-snap, and not immediately following, like the mid-credits scene showing Lang stranded in the Quantum Realm. This makes it the MCU's first exploration of a post-Thanos world.
When the pandemonium of 50% of people disappearing has passed, it does not mean that society is all of a sudden back to normal (whatever Thanos thinks). It means that half the workforce is gone, which could include elements of government, police, military and/or medical staff. It's a recipe for an apocalyptic breakdown. Yet, outside Scott Lang's/Big Ant's window, the world seems spookily normal - apart from the failed TV signal (which proves that the lights are on, but nobody's home).
What Does This Tell Us About The World in Avengers 4?
The world immediately post-snap is going to be a confusing, hellacious one, and it's a logical step to imagine the few remaining Avengers will be needed to keep the peace the world over and perhaps even provide accountability on the world stage for their actions or failure thereof. What Ant-Man & The Wasp highlights is that the impact of Avengers: Infinity War won't simply pass, setting the scene for a team in Avengers 4 that are ready to, well, avenge.
General Ross, a thorn in the Avengers' side since Captain America: Civil War, isn't confirmed to be dust. If he isn't, considering the fact that Rhodey hung up on him after revealing he was teaming up with the fugitive Cap and co., you can make a safe bet that he'd be on the Avengers' case regarding the global half-genocide that just occurred. After all, the Sokovia Accords are still in effect.