$4600 would prove wrong the theory that Bitcoin cannot go below $5500-ish, which is the guesstimated cost of mining one bitcoin that I've heard lately. So far it seems to be working. Every time it breaks below $6k it gets a huge buy that creates big candle of up to $400+.

This doesn't guarantee anything but it's another resistance to considering given past precedence.

As far as all altcoins going near zero... I am not sure the market as a whole is mature enough to realize how most altcoins are shitcoins and they just should be holding as much BTC as possible on their portfolios. So when the next hype for crypto comes, I still expect another altcoin bubble.