As usual, Apis gets straight to the heart of the matter---cost effectiveness and hive management. As usual, his analysis is right on.
IMHO, cost management will be of secondary importance to the hobbyists. They will be willing to buy this innovation "at almost any price" because of its convenience, its novelty or just for the fun of it. For those who have 2-10 hives and have no intention of getting more, bees aren't really there for the money but for the fun, the ideals, etc. The expense will be of little importance. Some might even take up the challenge of building them themselves.
The commercial bekeeper will, however, look at his pocket and make the calculations as Apis suggests..
However, successful hive management is of concern to big and small alike. Swarm prevention will not be the only issue. Northern beekeepers who have to develop and maintain winter stores of honey/syrup for their bees will have to work out a new way of managing the bees so as to guarantee the successful overwintering of their hives. Syrup can't be stored in the Flow frames, out of concern for keeping their honey as true honey. Honey that crystalizes in the cells over the winter would be a tragedy. As I see it, that means you would have to be able to remove and store the Flow frames during the winter, while another set of frames is filled up in the supers for the winter. The timing of when to replace the frames will require extra attention to the hives.
Another consideration which will put a crimp into "standard" management techniques will be the unsuitability of moving Flow frames down into the brood nest, lest they get plugged up with pollen. The flexibility of transferring frames from upper to lower supers or to the brood box is something greatly appreciated by those who work with deep boxes only. Those who mix deeps, mediums and shallows often express regret over their inability to move frames up and down to solve assorted challenges of management.
Flow frames, being (as claimed) too deep for the queen to lay in, can't be counted on to help build up a hive in a pinch. It would also seem to me that getting the bees to build these extended cells will be a challenge that demands precise management during heavy nectar flows, something that not all of us are blessed with or up to handeling.
Bottom line: As I see it now, I think that Flow frames will be a curiosity with a short life span. People will buy them, try them and retire them. Some keeps might stick with them for their novelty value, but until proven wrong, I think I'll be skeptical about their leading a revolution.