If BTC dominance would drop to 35-40 percent as it was back in 2017, all altcoins will raise in price and we would finally enter green market cycle. But I do not see this happening in the nearest future, so buy BTC and wait.
Agree, if the dominance of Bitcoin goes down, altseason will occur naturally. With the altitude of almost 5,000 coins and tokens, I don't think all altcoins will go up in price, just a few altcoins that I think will give profits to investors.