I definitely think that Segwit is already priced in, and has been for some weeks. This ATH had less to do with that than the fork. Four more days at least before SW locks in - we may see yet another ATH, provided BTC maintains levels above $3k. Any dip below that and SW will probably only restore the levels of this weekend. It would be nice to be proven wrong!
As activation of segwit nears we can expect price of bitcoin to peak to another ATH also.
Traders will go for speculating always well in advance that is the reason we are experiencing big leap well in advance to segwit activation. I believe price will keep roaring and may hit $4000 levels too.
I do not find any possibilities of corrections in between time even any whales want to book profits, I believe there could be more number of new investors and investments to withstand against them.