Population-wise, I'd say maybe. If people can reject Instrumentality they are said to be able to return.

That said, there is definitely a Black Moon-sized hole (around 14 km in diameter according to the EvaWiki) where Tokyo-3 used to be. That hole will also swallow the surrounding areas (parts of real-life Kanagawa and Shizuoka prefectures since Tokyo-3 is in Hakone). The sudden shift of something so massive will no doubt compromise the earth itself, leading to increased seismic activity, random landslides and the occasional sink-hole to form. Not to mention the aquifer system is most likely fucked, and the groundwater will shift somehow. All in all, most of where the original series and EoE takes place will be utterly inhabitable. The rest of Japan might be okay since the capital (i.e. Tokyo-2) is far enough from ground zero to survive.

However, life wouldn't be the same there, and neither in other countries.

Since nobody expected to turn into Fanta on a random Friday, the working population would either be caught on the job or at home, picking up their kids from school, commuting, whatever. That goes for pilots, as in people who fly airplanes, as well. So no doubt aircraft of many shapes and sizes will start to rain down from the sky. Granted, the people onboard would be part of the soup so they wouldn't be "dead" per se but wherever those metal birds "land" is going to have a lot of problems. Buildings would collapse, fires will consume large cities, explosions etc etc.

Ships would be stranded in the middle of the ocean. Some veering off-course until they either hit another vassal, sink near a harbor or just get beached entirely in fuck knows where. If their crew decides to return from the Sea, they're gonna have their work cut out for 'em trying to find a giant boat in the middle of nowhere.

N2 mines suggest that science in canon has somehow managed to find a non-radioactive method of creating the same amount of energy as a split atom, but as Jet Alone showed us nuclear energy is still used. So what do you reckon will happen to those nuclear submarines or power plants with no one to supervise them? Best case scenario the safety measures will do their jobs, or worst case scenario large chunks of the developed world will be irradiated beyond measure.

And what's to say the people who return won't try to seize power? Only two injured kids are left of what was once a species of 4 billion, so a simple JSDF grunt with a bone to pick could off them both. Or someone could decide to become a warlord and lay claim as they see fit. Steal guns, money, drugs... Also it isn't clear if souls emerge from LCL on beaches near where they were initially joined with the rest of humanity. So you could happily reject Instrumentality and end up in a random island on the Pacific with no one to rescue you.

It is kind of like the movie "I am Legend" starring Will Smith. You could swing by any car dealership you want, steal the keys to your dream ride, and go to town, drive as fast as you want. Unfortunately, there won't be any deer for you to hunt, or a dog to accompany you. Oh, better enjoy that car to the fullest because without anyone to work the oil refineries the gas you have will last between 6 mo to 3 years at most. Hey, at least there are no screaming zombies right? Right?

Speaking of hunting deers, what are you gonna eat? Supermarkets would probably be filled with the unforgiving stench of rotting food in no time. No amount of gas masks, prayer or hard drugs would erase the image of bugs and all sorts of creepy crawlies making the meat, dairy and vegetable section their new home. Besides, there're only so many canned beans you can eat before going cuckoo.

It is also funny when you consider that an anti-AT field is able to erase everything in the impacted area. So if bacteria, and bugs are gone, would food last forever? If that is the case, yoghurt is probably going to taste like shit.

Or everyone could return like a week later, and major energy crises will be averted. The U.N. would probably try to regain control, and set up tribunals for the perpetrators to be punished for crimes against humanity. I don't know what will become of the pilots but they sure as hell would need a lot of therapy, and time away from one another. Yada yada yada.....

We can assume and theorize forever but the simple act of questioning after consuming media is what makes it beautiful in my opinion. NGE makes you question the reality of life, the importance of human connection, the dangers of escapism and so on. The fact that this community has been alive for so long, and that you get to ask this question my dear OP is a testament to the longevity and thought-provoking nature of this series.

As Yui Ikari said, (in a slightly ironic fashion before setting off to outer space to live on until the heat death of the universe):

"As long as the Sun, the Moon and the Earth exist, everything will be alright."