Anyhow Ethereum is the one of the most highlight and most important role altcoin in ICO and other investment destinations.
For the likelihood, I think it's possible that Ethereum would be following the bitcoin's price movements due Ethereum seems playing an increasingly important role like as bitcoin to everyone and has been supported by various parties.
Don't know what you are talking about planned developments scenario in terms of price. Ethereum does have a highly centralized leadership and core development, but I do not believe they have any influence on price, if they did it would not have taken them so long to reach the thousand dollar barrier. They are probably disappointed in 2017 a few times, but with 2.0 announcement they are going to be pleased with the performance this year.
And for the first time we see it no longer ties to Bitcoin price developments so it is now fully maturing into its own coin independent of Bitcoin price.
I agree, now the price of ethereum can not be affected by bitcoin anymore. and I believe ethereum will make a surprise in 2018