I think what you are asking for is already being done, it just depend on you, what is your denomination for your portfolio, if it is BTC or Fiat, some people don't care about the price of BTC, what they consider is the fiat profit. Whether you likely or not, market is in cycle whether BTC dip or not
There are in fact Altcoins that being paired into USD like LiteCoin, NEO, Ethereum, USDT etc.
That is my point that when almost all Altcoins are being just paired into USD ratio then Bitcoin's dip cannot affect Atlcoins price anymore.
Because now, for me to be able to not losing my Crypto Assets is I am going to convert them into USD so that when those Altcoins went down, I could even buy more coins. That's would be better than watching all the coins are drowning on blood and you can't do anything because you just can't sell your coins and buy other coins.