ETH pushing ahead towards $700 could open the door to further upside, as there appears to be little resistance then until towards the $900 and $1,000 mark.
That's true but it will be a very difficult thing to do. This time the movement of ethereum is pegged with bitcoin. We can't deny the fact that if bitcoin is controlling the bullrun right now. If ethereum is still following bitcoin and ATH is just a dream. Ethereum must leave from the domination of bitcoin. Ethereum needs to be doubled to achieve its ATH.
I doubt this will happen shortly.