The biggest problem with large numbers of people moving to another country lies in the bureaucratic bottle neck they all must pass through. Expect to spend several months to several years before you are done. When I moved to Mexico, it took me about half a year to get through the preparation and the initial paperwork. Once I was in the country there were additional fees and paperwork before I received a permanent resident permit several years later.

If large numbers of people want to move, expect requirements to get steeper as people in the receiving country begin to worry about the consequences of a large influx of foreigners. Expect the required personal qualifications to get stiffer, expect the fees to get steeper, and expect the delays for bureaucratic approvals to get longer due to the increased workload.

In many countries you would not have to move immediately, so a good plan might be to get approval now rather than when things get tough.

Expect misinformation and changing requirements and procedures. Expect false steps and mistakes. You'l want to get as much information as early as practical so you can make realistic plans. Even then patience and flexibility are required.

In summary, do it now because if you don't, it may not be practical later.