Remember that this whole year started with the extreme fear of the scaling War (even I wanted to sell it all). At year start Bitcoin had still 89% of the market cap, and lost during this War it's leadership to 40% (traders fled to alt-coins). Now that this War is coming to an end, and looks that the original Bitcoin survived, there is a rush back (of course helped by the free dividend).
I see no reason what so ever to believe that money will move to alt-coins again. It will stay there as fear is gone.
View attachment 179217
By the way: bitcoinCash will probably not split. The run up has more to do with a pump for the S2X-fork chaos (they hope that S2X will fail and miners flee to BCH).