If I were holding a large amount of Bitcoins worth millions of dollars, I would start cashing out right now before it's too late.
Think about it deeply, either split happens and value halves in less than half of the current value or everything will go smooth.
But if split happens then imagine that your coins will be priced 50% less for almost 2-3 years before the market gains the trust and starts growing again.
Are you willing to put millions of dollars on hold for 2-3 years?
Is this really what everyone expects to happen, a 50% drop?
What is the effect on ETH LTC? Same ?
Who cares what happens to ETH and LTC, they are separate from Bitcoin, if I'm not saying when but if a chain split happens then yes price will immediately drops 50% wide spread across all the exchanges, another possible scenario is that everything will go as smooth and without any major loss of blocks found by miners then price will increase further more, who knows maybe it hits $6000 within 2 weeks after the fork. so basically we're looking at a 50-50 situation, however I'm not saying Bitcoin will lose it's value forever not at all but since there are billions of dollars at stake market might react badly and we could see at least 2 years of distrust and doubt but after that it will start to roll.
I'm just saying that such a scenario is not far from happening.