I can see New Mills being moved from Division 1 South to Division 1 North with Frickley Athletic and Burscough coming down from the Premier League and Ramsbottom United from the NWCL with Harrogate Railway and Cammell Laird being reprieved from relegation.
Surely the relegation of Northwich (to the South presumably) will mean that Frickley will get a reprieve?
My first reaction when I read that you could see NM being moved North was "not a chance", but having studied things for a while, I can actually see the possibility of that happening.
With no promotion from the Northern League or the NCEL, the only teams likely to be promoted to Step 4 are Rammy from the NWCL (as you said) and Gresley from the MFA. Gresley would undoubtedly go to the South along with Chasetown, Mickleover and Northwich.
With the relegation of Woodley Sports and the resignation of Durham City, the North division would still be two teams short after Rammy and Burscough are factored in. This could mean that NM and one other (Sheffield maybe, or even Northwich) could be placed in the North. If it were to be done purely on who is furthest North, it could even be Goole Town and Brigg Town.
This would suggest (in my opinion) that Quorn and Shepshed would be reprieved in the South, although a news item on the NCEL website suggests that these two will be relegated. Personally, I can't readily see a way to work it other than a reprieve for these two unless they also promote Runcorn Town and Bootle from the NWCFL, but based on track record, there isn't a snowball's chance in hell of that happening.