The Indies First movement will attempt to find out.
I appreciate what the authors are trying to do here; but the independent booksellers' business model is fundamentally threatened because they can't match the pricing and selection of Amazon. Staffing a small corner bookshop with a gaggle of mid-list authors for a day isn't going to change those underlying factors.
My fear is that this is more of a feel-good gesture than anything. Perhaps I'll be proven wrong. We'll see.