Somebody told me that if I travel too far from my house, it will disappear (possibly with my treasury). Is it true? Will the chunk change if I travel too far? I travelled across tens of thousands of blocks and the house was still there, but I don't know if it will change with being millions of blocks away. If it does, can I preserve the house with a map?
I'm only aware of one very specific situation in which chunks are altered after being generated. Deep ocean biomes which have not been inhabited for more than three minutes may have ocean monuments spawn in them; the three-minute limit appears to exist specifically to prevent the "my house suddenly vanished" problem. Other than this, the game does not modify existing chunks by itself.