To your first point, no I didn’t say anything about this because I didn’t think of it – goes back to the dabbler versus professional! Everyone would trust the official content but it would clearly be confusing for newbies.
To your second point, never! Nobody goes back and updates blogs etc as they’d rather put something new out – slash and burn, never look back. I can’t imagine how much effort goes into updating Trailhead every release. Somebody must feel like Sisyphus.
I am coming to Dreamforce – be great to talk about this some more and find out what else I haven’t thought about :)