It will give a big pressure to the altcoin but remember about bitcoin will not be getting the bullish trend forever. So many altcoins holders are shorting bitcoin and bet all of their altcoin today and we will see so many people will be getting another lost again in the future when altcoin bullish will start.
the market is always like that, when bitcoin rises so many people will sell altcoins for bitcoin. and vice versa when altcoin goes up, they will buy more altcoins, and like that continue. but we have to do the right planning on our assets. if an asset that will have the ability to grow it seems we have to hold it up.