Over the years I have noticed that most alt season started as follows:
1. $BTC pumps first.
2. $ETH $BET & $LTC coin pumps next, leading indicators of the Alt season.
3. Big marketcap tokens next. Usually top 20 on CMC.
4. Then full blown Alt season.
If that really happens, I am sure many people willing to wait for more until that day comes. They will try to buy as many coins as possible and make sure they will join with the altcoin season. But I guess that we still do not have the right time when the altcoin season will come, and maybe bitcoin price will still rise after this.