Is there any word yet on whether the market will become a permanent fixture after Christmas?
Not knowing what the arrangement is between the organisers and the Horniman, I think it is more a case of allowing the market and the traders that have taken the plunge and opened shops here to work together if they can, and want to, as other people have suggested:

"To my mind the thing to do would be to set up a 'Totally Locally' stand at the market"

That seems like a good idea to me. That might allow local traders who may not have stalls to advertise and promote themselves?
I'm very pleased that the market is a success, i welcome it, and there is obviously a demand for it, but i think recognising that some of that success has been made possible by the fact that people may be shopping more locally for speciality foods etc now because more small shops have been brave enough to open here (and the FHSoc have done sterling work to encourage that, of course) would be good.
Personally, i'm going to continue to spread my shopping between the market (while it's here?) for a few things and the shops i like to use and want to support locally.