In 1859, Charles Darwin released his "Origin of Species By Natural Selection." It was as disruptive as learning the earth is round and not the center of the universe or perhaps as shocking as microscopes discovering a microbial world.
In the scheme of things, disrupting belief systems with new knowledge is often considered a curse. Just look at the splitting of an atom, bringing populations to their knees in fear.
Most of the worlds we have discovered are from the Earth down to microbial, atomic, subatomic, quantum, and likely even more worlds we cannot perceive. If we put this into a context, Black Plague brought down a huge portion of the world population and the culprit couldn't be seen with the human eye. We assume if something is bigger it's threatening, but it's what you can't see that could get you.
Disclosure is going to be done in stages if it's done right. No one is going to accept it right away, like Darwin's theory. Darwin's theory didn't kill religion and beliefs that God designed the world. It just explained how those having the right features for their environment last longer and continue to breed. The two concepts can live side by side.
And so it will eventually be when humanity realizes they aren't the highest run on the ladder. We will have a period of rebellion against the truth, absolute fear, trying hard to keep things the way they were. But, you can't put the genie back in the bottle. Like the nukes, you can't make that killing knowledge go away, so you learn to respect the power and responsibility.
The strange thing about disclosure is it's not something we can resolve readily. Unless these alien beings want to come down and talk face to face, we generally have knowledge they exist and that they visit now and then, but like shy creatures, we don't know their motives or capabilities.
We know they're there, we just don't know who they are.
There are plenty of things mankind has had to deal with while not having all the answers. If anything, this shows us that we don't know a whole hell of lot about the universe, technology, and a whole spectrum of science that has yet to be uncovered.
In private, governments have likely been trying to reverse engineer or communicate with surviving crash victims from unknown worlds. The public hasn't had that much time to decide what it's about, but those with a vested interest, i.e. the trinity - government, religion, education do have a vested interest.
When disclosure occurs, the government will look very guilty for hiding from its citizens something that should have been up front decades ago, allowing generations to be okay with notion that we aren't alone. Instead, it will be a slapped awakening overnight. This is not going to give citizens a warm fuzzy feeling.
We will ponder, what else do they hide from us?
Religion is a business. It will have to make a spin on this situation in order to perhaps bring in more parishioners. The likely way it will handle this is one of two ways - either the aliens are a sign of the end of times so please repent, or God seeded other locations in the universe and Christ visited them all.
Educational systems are pasteurized and honestly they hate to say they don't have all the answers. There will be an agreed upon storyline and they will push it from colleges and textbooks to museum displays. How will they take disclosure? I believe for a time, they will ignore any reference until they have a concensus on how to mention it. Just look at the out of place/out of time artifacts and megalithic structures, pyramids, they want to attribute to the indigenous people that are presently in these locations? It's rather like me claiming I built my house, when I bought it from someone and moved in. Education will be the last of the trinity to deal with the subject.
The first of the trinity to discuss aliens are the governments. They have a fine line they must dance along because revealing all they know is revealing technology secrets. Of course, governments would then focus on communication and gaining knowledge from these otherworldly intelligences. Whomever has their gear, rules the Earth. Secretly, the governments have known this all along, but now the public will be in the truth.
How will humanity as a whole deal with aliens? I suspect a lot like how they handled the UAP meetings. If they don't encounter aliens, nothing has changed in their lives. It's rather like an announcement of a new creature catalogued in the forest. If they are that hard to run into, you forget altogether that they exist.
Will we be better for knowing?
Humanity is mortal. We tend to focus on things like food, procreation, shelter, water. If we don't see anything change in our daily lives, we are on a happy autopilot. Just so long as the aliens don't start walking among us, we put that info on a shelf and continue with life. After all, isn't that what we had to do with the bomb? I remember as a kid, standing on the playground watching my friends race around during recess. There was a speaker in the corner of the asphalt that was used for bomb drills. I was a kid but my mind was thinking - when will it drop? We will all be gone in seconds. But, as an adult, that knowledge doesn't haunt me anymore. It's just another thing I know about.
So it will be with alien disclosure. Just another thing we know.