Probably that is bad for altcoins prices and i am very sure that altcoins will be affected if bitcoin is dropping the price, if this gonna happen we should hold our coins and wait the bitcoin price go up and do not make get panic selling because this is not good for your profit.
I would also add:
If you see an altcoin regurarly performing upwards when BTC is going down, then maybe you should give a closer look to this altcoin
