It depends on the general fundamental news in the market. If they are negative, even a successful launch of Constantinople won't give rise to growth. The ether will begin to grow at about the same time as bitcoin. I hope it will be in January, if Baktt opens and starts to work.
Now you can find news about the launch of the Bakkt platform. Dates will be changed. It seems to me that even with the successful updating of the ethereum, he will not be able to overcome the price of $ 300. There is a possibility that even in 2019 ethereum will not cost more than $ 500