Might be flawed!

Point 1: You did not account for the lightning effect.

Lightning does transactions out of the blockchain. The single lightning start/close transaction will tend to have higher value. This could explain all your chart observations. I did not calculate the lightning effect on that figures, neither you. Thus it is an open question. Your high focus on Bitcoin could also have lead to a misperception in that sense. I think the whole analysis must be redone.

Point 2: Media hype = bubble != fundamentals

Media hype is dangerous, pushes market cap to non justifiable levels. Less (or stable) media attention lets fundamentals to improve with less disturbance. Sure, even I having 80% portfolio into crypto do not read as many news as in december/January. But i am not jumping off. This attention analysis was interesting, but i do not agree with your conclusion (or follow up).

I just think that the general pattern you described would be predictable and not indicate a crypto recession. The fundamentals for 2018 also speak very much agains recession or stagnation on crypto.