There are many altcoin which grew around in market. With such profit, risk follows. While Altcoin is riskier when compared to bitcoin. Litecoin is older than ethereum but is an improvement to bitcoin as litecoin is four times faster than Bitcoin, it's grown to be one of the best altcoins with its current trading.
It might be a litecoin season too for bull run likewise etheruem has done in last btc halving. Apart from that, there are new altcoins whose present in the market will be a great achievement. I don't want to mention names but project are leading their coins strong lately. Lets see if the halving is going to cause a bull in altcoins.
Yeah, let see what will happen next, a few months from now. And I believe there is probably a change happening and quite different as we've seen today.
But talking about Bitcoin's stability zone, I doubt that we could find it. Volatility stance for it and therefore, we could never see there is stability zone. The market moves freely, it goes up and down at any time, the same thing as it happen to altcoins.