There are huge number of Alts in the market that have almost infinite supply of coins. Moreover investor trust has been shattered mainly beacue of alts that proved to be scam or are abandoned by founders once they gathered the necessary funds. If there is an Alt season, then probably top 10 or 20 Alts listed on coinmarketcap.com might go up. I don't think all alts have the capability to go up incase of an Alt season.