We have two Bromptons in the family and I use mine every day for a mixed mode commute. I see various other folders on the train and none come close to the Brompton for useability. I suppose someone will come out with a real competitor at some point but they certainly seem to making heavy weather of it.
Although I do applaud the evolutionary development strategy I would dearly love to see an all new Brompton incorporating everything they have learnt along the years. I imagine that they must be thinking, at least, of electrification. After all, as little as 5 miles range would satisfy about 95% of Brompton users.