Everybody is pulling money out of their altcoins into BTC to wait for the hardfork and collect their bitcoin gold. But as long as there are hardforks on the BTC agenda, don't expect a large pullback.
This is the usual case. Prices of bitcoins go up then altcoins go down, but when prices of bitcoins go down prices of altcoins go up. It has never failed. So right now prices of altcoins are very cheap, probably this is the best time to buy alts and dump some btc as probably this is another all time high that will just be an all time high. It will probably go down in a few days or weeks then prices will then again move sideways. Or if a trader prefers not to buy altcoins, selling at all time highs like this for fiat is another option which is the next big thing. Then just buy back when prices dumps.