What do you think these other things could be?
I generally assume he was moving on to battle an illness, and that he lost the battle and died.
This is so dramatic

I think that he moved to other projects, people who innovates can not sit in one place, they have so start doing something, maybe he is searching a way how to create something bigger than Bitcoin
Well said, innovators can't spend the time and the mind on a single project. Once they innovate automatically they'll go for a bigger innovation pushing themselves harder and harder. This way Satoshi moving to find a bigger way isn't a big thing. This is like one beating his own records.