I really dont know what the HF is going to mean for ETH, but there can only be one clear winner and if its going to be unstable or have an uncertain future, we will see more ETH of both chains potentially get dumped.
Probably "new" investors will be confused what choose and most will go with main devs but some idealist wil stick with orginal chain.
Anyway it is free money creation like from central banks.
It won't cause mass dump now ETH but no new money in future is very possible with one chain situation is more clear for people.
And now investors have to think that ETH can be divide into infinity on the way.
Winners of that will be probably ETH kind platforms smart contracts etc.