I don't think people will ever lose interest in earning money. Some people may, but those are very special cases. In economics, it's said that Human wants are insatiable while resources to satisfy them are limited. That doesn't mean we'll ever stop trying to satisfy them and as such means we won't ever stop trying to make money.
For those that don't want money anymore, they are either
I) filthy rich
II) have attained spiritual freedom or
III) both.
Either way, the people that fall into these categories are very few.