Great to see HSK5+ is in the works. I’m definitely interested in seeing this develop, but I still have 250 lessons to work through before I get there. 
HackChinese says I have 25% of the HSK5+ vocab so far. I’m about to start HSK3 on LTL, about 60% through HSK4.0 in HackChinese, almost finished New Practical Chinese Reader vol. 2 and soon to start vol. 3 in my uni diploma, but still on HSK1 in Skritter! All over the place…
Personally, I’d love to explore Chinese literature and history. I noticed there were a couple of topics like that in HSK5.0 like Lu Xun, the Monkey King.