As humans we are integration machines. We need to take in novel information in order to combine it and produce new novel information. HN definitely helps with that, as the bullshit here is at a minimum with interesting technical information all over the place. Its honestly a gold mine, similar to what Slashdot was in yesteryear.
I have a similar question to OP: when HN dies like Slashdot, what's next?
Honestly my guess is that I won't get a solid answer in this thread, but some time after HN dies I'll just find myself on the next thing just like I found HN years after I left Slashdot