In my view the future success of Ethereum will depend on Caspar, the move from proof of work to proof of stake.
Currently Ethereum is the leading smart contracts platform by market capitalisation but it suffers greatly from low transaction speed. This was illustrated by the Cryptokitties issues which tied the blockchain in knots.
2018 has seen faster smart contract platforms launching under PoS (EOS for example) and these will start to eat into Ethereum's first mover advantage. The longer Ethereum is lagging behind, the more will be developed on the alternative platforms, the more likely Ethereum could lose its place as the leader.
So for me it depends on the timing. Caspar is already out in testnet form. If it is implemented fully in the next few months, Ethereum could see a boost. The longer the delay, the more likely the Ethereum price is to slide.
Just my view, not financial advice, do your own research, never invest more than you can afford to lose.