That trendline intersection is pretty amazing, to the day, well spotted!

I don't think that BTC will fight back like before. Remember that market dominance will have to change over time. We have so many more altcoins now, properly established alts, not just little shitcoins. BTC is no longer competing against 1000 alts or less. As the number of alts grows and they pick up value in their own right, so the market dominance of BTC will slowly wane. This doesn't even mean a relative price drop for BTC, just that the market is growing.

Having said that, I do believe that December/January was a game changer for the market. BTC raced up and slaughtered the alts, but then they fought back and slaughtered BTC even worse. I would be very surprised if BTC ever got back to the 50% mark, alts are been taken far more seriously these days, the market isn't just all speculation any more!