Some interesting points if you are what I would class a traditional soul fan. The music of the likes of James Carr, Bobby Bland etc, is really now confined to people's own record and CD collections with no interest whatsoever beyond. It's a tragic shame that 30 people turn up to see Lou Pride -especially as his repetoire is so much richer than "I'm comun home in the mornun". I remember when I first tracked him down in the 90s and interviewed him on radio, his only knowledge of the UK scene was that "I'm comun home" had been a "number one hit in the UK". Of course I had to disavow him of that belief straight away. How disappointed he must have been to see a crowd of....30.
New soul music generally attracts low sales. There is the odd trend bucker, but not very often. I mean by definition a press of 500 of a new release means that it is destined to remain extremely obscure. Many of the 500 presses don't even sell out.
The northern scene by contrast is a club based scene based around dancing and obscure records and has nothing to do with what goes on in the wider contemporary soul world. It always has been, however that too is fragmented into factions, some of which are positively struggling numbers wise. The oldies brigade, newies fans etc etc. It is wrong to lump northern in with the wider soul scene, as the two are totally divorced from each other.
As for the Dells at Hammersmith, I really don't think that would have worked. At Trentham, I was annoyed at the time when some of the people were getting openly bored when they were singing things like "Standing ovation". But why wouldn't people travel up the M6 to see such a fabulous group? I think if there was any chance of them filling the Hammy O Burton would have seized that opportunity. But I don't see it myself - London based soul fans - it's hard enough to get them to cross the road to go and see an act .
I have seen this type of article before, it's all been said before, but it is sometimes worth taking a check as to where we are. The northern scene will continue to evolve for some years yet (unfortunately for me it seems to be ever increasingly oldies based with in too many cases lowering standards - but that's my opinion). But I think you have to carve out the northern scene from the rest of your article, simply because northern is not linked to mainstream soul.