The biggest factor in my opinion is whether you are truly accepted in the new country. Countries such as the US, Canada, Brazil, Australia, Mexico and many others especially in the Western Hemisphere are full of European immigrants like yourself so you feel quite welcome. I personally would be skeptical of moving to a country which is dominated by a few local cultures such as China, India, Russia, most of Europe, and most of the world for that matter. It makes a big difference whether you feel that you have to assimilate or if your native culture and adopted culture both become your identity.

Most older developers I have seen chose to leave the field, they are not forced out. A lot of the older developers didn't study any computer science because it wasn't mature in their time so they have trouble adapting as technology changes. This leads to a large subset that don't keep up their skills so when they get laid off they struggle. If they stay up date and still have energy and enthusiasm they will be welcomed with open arms.