As for when the Altcoins season will come, I think it depends on when Bitcoin will stabilize. Now is the time for Bitcoin to perform. As Bitcoin gets higher and higher, when it stabilizes, I think the Altcoins season will come. According to 2017 Years of experience, I think there will be a good performance in 2021.
Bitcoin has taken the spot light from every altcoin and it reflects in the market many alts are now in red if BTC continue to rally in 2021 many new investor will likely to buy bitcoin rather than alts and those struggling to stay on the market may likely loss its value.
You should not forget the market cycles, in the next market cycle BTC will give back the same light to the altcoins which will survive during a bear trend. It is like a stress test and the reward will go to those who can wait patently for the right moment to sell higher. A kinda old trick for all sectors of financial markets but still works.