IMHO Mr Branson would have run them at a loss, if only for the kudos he would have gained for being the only Concorde operator, and the "British" thing that puts two fingers up to all the other airline operators too.
On the flipside, the operational costs of these beautiful planes is nearly double of an Airbus A380, so for how long Concorde would have flown afterwards is a debateable point because of Branson's financial position at that time.
There is not now, and will not be for the foreseable future ANY aircraft that does what Concorde did, at the time it did it, over the distance it did it, with the obvious affection it still has for such a fantastically beautiful aeroplane that looks as good today, as when it was first introduced as "Concorde 001" and coming from Bristol, quite near to Filton where she was concieved and first flown from,AND where she is still today........I am still convinced it was ahead of its time, and still a viable aircraft.