I've seen mobile homes that are 20 years old and are ready to be torn down while others I've seen that are 40 years old and although outdated designs inside the mobile home is in otherwise good condition.
I don't think a mobile home would last 100 years although it could be possible. But to make a mobile home last a long time you have to take care of it and maintain it like any other home.
Even conventional homes can go downhill and be ready to tear down in 20 years if it's not taken care of.
There's conventional houses that are 100 years old that need torn down while others are over 100 years old and look great because they were taken care of.
Take care of any home and it will last a long time. You should maintain a home as a house is a huge investment and purchase.