It's a good guess. There's nothing that can stop bitcoin anytime soon until the segwit2x morons start talking about hardfork again, ruining the price. But consider that during bitcoin crashes, all alts seem to crash too...it's difficult to guess how alts will react. I don't think it's as easy as saying "BTC bullrun = alts bear" and "BTC bearrun = alts bull". From my experience, the best time to buy is during the dip of whatever you want to buy, just pay attention to what you have on mind.