For me, one big league wouldn't work unless you got rid of all the "star names", as too many clubs couldn't afford to use them..
And that would mean an uncompetitive league..
With the fans who are used to seeing the "star names" (at the clubs with mainly the best attendances), losing interest in watching a lesser standard..
An 8 team "super league" with six of the current clubs in the top flight, ex Brum, but adding Poole and Glasgow would be my call..
Organically the top 8 clubs for attendances..
The rest are then an amalgam of Championship Lite/NDL level...
Meaning clubs don't overstretch their natural level, riders are in the large majority semi pro, (have one "Bomber" per team), and admission costs then reflect the semi pro standard..
Could bring back IOW and Kent meaning even more fixtures..?
DU is still there, but it needs to be currently, but you do get a flagship league to market the whole sport off, and the 2nd tier is then becomes the natural feeder league for UK lads wanting to get into the top flight, giving these riders plenty of opportunities to race...