I think that a lot of altcoins will follow the trend if Bitcoin enters into a full on bull market again. But I expect a lot of the money in alts to be drawned away to Bitcoin as we enter the price discovery mode. Those are going to be some exciting times haha
Of course, most of these altcoins are following the trend of Bitcoin so it is expected already that they going to follow if Bitcoin goes bullish. Just don't forget to choose the worthy coins for your investments and choose the top 10 to 20 coins in marketcap.
Top 10-20 is the "safe" bets, but they most likely wont be the best performing alts out there. The bigger the risk, the bigger the reward.
Once BTC breaks its ATH, it's gonna make people FOMO into the market again, which will create an even bigger "bubble" than we saw in 2017. Sure Tether propped up BTC, but we've got way more stable coins this time around, so you could speculate the next run to be 5-10x as big as the last one.
I'm accumulating BLOCK, and ADA like a mad man, at these crazy low prices, ADA is a safe investment, and BLOCK the most undervalued, diversification is key here really.