We dont know yet if the etherium will be going the ICO king, Because they have so many altcoins are now that have a chance to be a ICO king. Some of them are a potential coins and for long term. We can't mention of which altcoins it is maybe we need to wait of which of them are gonna be a king ICO.
I think we can say ETH is the king of ico in the present moment when most projects use eth as a platform, and with so many overwhelming projects, there is no reason for us to deny eth the king of ico. But the future will be very difficult to say because the market is in a fierce competition, while the opponents are becoming stronger, eth still goes down and shows its weakness, I very much doubt that the market will have a coup against the king in the future