he is into 'other things' could mean he is up to bigger things, bigger than BTC. it could mean he is up to set up another project but we are yet not seeing it. but this is if he is still alive.
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.
i always thought he was kidnapped by The Adjustment Bureau but i did not expect he got ill and died due to it, i hope its not tuberculosis because it certainly isn't bigger than BTC.