I think it might be good to sell some coins.. It is too dangerous. There are safe havens like ethereum so they can go there..
I do not think there is going to be a safe haven, if bitcoin crashes I think all the cryptocurrencies are going to crash with it since confidence in bitcoin will being to erode too quickly and people will panic and will sell their coins at whatever price just to be able to get away from the crash, you are still on time, you get out of the cryptocurrency market or you hold and wait for things to calm down.
Bitcoin is the King of all altcoin. It price may vary day to day.But upto know ,their is no altcoin will replace the bitcoin. Due to trading, inversing and some factor, the price may vary.Many use bitcoin for their Online transaction ,purchase. If this continues mean.On one fine day,bitcoin will replace the dollar. Atlast replace entire paper currency from the society and make the bank no more.Long term bitcoin holder can sell their bitcoin after second week of August.