“I ( should ) be very surprised if they send CH back over hurdles because, if so, what was the point of Southwell ?”
The original point of Southwell was because they had Sir Gino for the Champion hurdle in mid January (fresh from strolling up against race fit horses at Christmas) at the time when the Southwell race was being tailored specially for CH with the extra prize money and all the razz. Then, after Sir G bust himself, they got Yogi on the case for CH. They still had to go to Southwell rather than the Kingwell because a) it would have looked very churlish to get all the special treatment from Southwell then not bother turning up to the race designed for you and b) it gave a bit more time for the Yogi schooling, plus if he fell on his face in the Kingwell it squashes one dream, whereas to go to Southwell keeps both dreams alive. The Kingwell was Schrodingers hurdle race, Southwell was a way of avoiding looking inside the box, whilst still doing something more purposeful and less likely to generate accusations of cowardice than a Newbury gallop.
Keeping dreams alive as long as possible for owners is one of the most important skills for trainers. Unless you think the dream unrealistic and it clashes too much with your plans, then you run Spindleberry at Leopardstown (for example), pat the owners’ slumped shoulders and console them with the mares’ chase.