I prefer the way it is now. Safety first.

Most flight delays come from the limited capacity of airports in terms of
maximum number of take-offs and landings per hour. The airspace design is not
the source of these delays. And the reason the capacity of airports is often
reached is that many airlines have too many flights, especially small flights
on small aircraft instead of big flights on big aircraft. And the airlines
all want all their flights to land and take off at the same times.

So it's really a problem of airports, not airspace. If NextGen were
implemented tomorrow, the number of midairs would dramatically increase. Slow
(very slow!) implementation is better. In fact, they are already going too
fast.