bitcoin is about to enter full-blown crisis mode over zcash

Nah

if zcash trades above $10k while btc is still sub $100k, then absolutely yes

Despite being pretty bullish on zec, I think that's unlikely, tho possible. Also it's happened before. For one, ETH got to ~30-40% of BTC mcap at 2017 bull peak if memory serves. Yes there was plenty of flippening talk and a lot of annoyed reactions from bitcoiners, but no one was in crisis mode.

no, eth reached ~85% of bitcoin's mc at peak ethbtc ratio in june 2017

From memory I was doing: BTC ~18k at ~17.5mm supply in early 2018 = $315B mcap. ETH topped at ~$1400 on ~90mm supply = $126B 126 / 315 = 0.4 But ok checking the charts, BTC supply was more like 16.8mm and price was more like $14k when ETH peaked a month after BTC peaked. That still only gets you to ~54%. Regardless, anything over 10-15% having happened already makes my point. And higher % for that ETH event makes my point even stronger if anything.