I always said i would die on the hill of not having English regions. As a Saints fan I'd rather wash my eyes out with bleach than merge with the other East Mids clubs.
However taking a breath i look at the IRFU and Leinster etc and think would this have happened in Ireland given the system now. I look at the community game, pro club attendance across the globe and it appears rugby is dying on it's knees.
In reality the fault lies with Prem rugby, and the owners of the clubs.
Your overcomplicating it IMO.
You don't need regions, you just need the RFU to own enough clubs to play in a league above the existing league structures with no relegation.
The clubs would come from existing clubs and ideally be those with the biggest crowds.
So your looking at:
Quins
Leicester
Bristol
Bath
Gloucester
Northampton
Exeter
Saracens
Are Sale big enough? Are London Irish big enough? Are Newcastle big enough? Avg attendances would suggest a severe financial assessment needs made. Although against that, they are either in cities of their own (Sale/Newcastle) or are sharing one of the the biggest population centres in Europe (London Irish).