One major factor is setting the price is the estimated product that will be sold. If Sunset thinks that they can only sell 300 sets the project is probably DOA. If they can sell 500-600 sets maybe it is a go. If they can get firm orders for 800-1,000 sets I would say all doubt is removed and it will be done. This volume would spread out the design, tooling and material cost and thus push up the profit.
But we already know this. Now it is up to Sunset, Atlas, MTH, Lionel etc. to start the ball rolling.