Do you reckon it is more likely that new ASICs based on 7 nm chips won't reach the markets before second half of 2018?

IMO I would say this is for sure.

Chip manufacturers are saying something like this:

https://www.hpcwire.com/2017/06/13/globalfoundries-7nm-chips-coming-2018-euv-2019
http://www.androidauthority.com/who-will-be-the-first-manufacturer-to-7nm-757916

So how long does it take to develop new ASIC models from these chips may take some time so maybe it will be 2019 until retail level can buy products based on these chips ?!

Hopefully we will see a lot of new ASIC manufacturers popping up -> lower prices and more availability. Maybe new unexpected players from Russia or other countries ?