I really feel for Welwyn north passengers. I suspect they will be skipped lots and WGC and south will need to get used to all stations.
In the 2018 timetable there are also the half hourly Kings Cross to Royston services calling at Welwyn North, Hitchin & stations to Royston (or vv in the peak direction) - hopefully these services are still 365s !
So Welwyn North gets 4 tph in the peaks, 2 of which are non stop.. WGC gets 2 Thameslinks plus the Moorgate services.
Hopefully an 8 coach 387 can take over the 07:55 Cambridge to Kings cross service shortly - this is currently a 4 coach 321, I think the only 4 coach service towards London in the main part of the morning peak on the GN outers? It would need to use the SDO for the villages.