Yea you are right. The number of BTC maximalist is increasing during BTC bull run but after the start of the altseason rally, you are going to see how the things are going to change. Just wait a little bit more. BTC dominance starts to decrease and this could be a sign for alts.
After enojyed the ride of bitcoin over first six months, whales will start to enjoy rides of altcoins. They will do what they have to do to help altcoins start moving. I don't think within this year, we won't see altcoin season. I also agree with you on the good indicator for altcoin season, bitcoin domination has gradually decreased.