Drone racing is already a thing sort of. It could be the
world's most boring sport. Bunch of buzzy little things
flying around in circles.
But watching the incredible video linked, I think that with
an interesting course such as this, the view from the
drones might be very exciting to watch.
linked bike course took massive amounts of
preparation, this wouldn't. Property owners around the city
would participate by saying "You can fly in my front door,
through my living room and up through my chimney. Signs
on the wall might say "Hi Cathy! Proud of you graduating!"
or the like. Businesses would do the same, lining the
course with advertisements, obstacles etc.
There wouldn't be much prep cost as the volunteers along
the course would get everything ready.
The first link shows how cool this would be, but unlike the
bike run, you'd be flying through tiny windows, into and
out of sewers, over skyscrapers or through the offices on
the top floors.
Charge each of the participants a few hundred bucks or so,
you've actually got some substantial prize money if the
course is long enough.