It seems like the best time to sell altcoins is over, as we know that the best history of altcoins is 2017 until March 2018, almost all altcoins prices go up because they follow the trend of bitcoin prices, now we can only survive and wait for a miracle.
I still believe that such time would arrive again, because the market runs always in cycles. Sooner or later we would come to the point when BTC dominance would fall and leave space for altcoins to grow.
Not only you, many believe that alt season will come again, and it will. It will not be only an alt season, like always we will see bitcoin making new records, and some alts will follow that and they will make their own records too. Every time after bitcoin halving, entire crypto market make a progress. Take a look what happened in the past, same will happen not once again, it will happen couple more times.
All of us would like to see bitcoin at 1M dollars, that will not happen after next halving, maybe the one after next, or I don't know, all I know is that every halving will get us closer to that price!