Changing Stores - Dear Apple, the world is getting smaller

I have lived in Japan for around 5 years now and I created my apple id here. I have made many purchases in the online stores. However i might be moving back home next year, which means i will not have a japanese billing address, japanese credit card or anything japanese. Thus next year i want to change the store to my country and update with proper billing information and working credit card. I have seen the articles about changing the stores. I have also read about a lot of bad things that follow it.

Basically, what i am asking is - what happens to everything i own? no updates, nothing for iOS?If something happens to my mac: no new Os, no ilife(all digital now associated with your apple id)?

And a follow-up - should i just not buy anything for the next one year because i will lose it anyway when i move back home?

I know many people are having the same nightmares. People move a lot nowadays - job, marriage, economy etc. The world is getting smaller and smaller and yet Apple fails to do something about it.
Anyone with recent info on the topic? Recent exp? Past exp?