Can bitcoin addresses be programmed to send funds to other addresses when reaching previously determined thresholds?
No. For multiple reasons. The most important of which is:
At the protocol level, addresses don't exist, and can't be programmed.
I've been thinking about the ramifications of "programmable money," and am now wondering how programmable the currency itself is as opposed to how sophisticated the applications can become that can merely make use of information in the blockchain (though this is also extremely interesting).
(rambling about "imagining" and "changing of the world" and "mind-boggling" and "trying to fathom")
;tl,dr
Please pass whatever it is that you're on.