As for 44/8, there are still those that use it, taking it away would mean having to renumber all of the equipment on that network...
No, trying to reclaim IPv4 addresses by making people go through herculean efforts to renumber their networks is not the way forward and simply delays the inevitable. IPv6 is the way forward, start pushing that, and get more people using it.
It would take years to arrange the return of 100 million addresses compared to the demand for a few billion addresses with even conservative growth.
Edit: I wish there was an updated version.
That's enough to find out that this particular one is called a Hilbert curve.
This page has similar images from 2012
Consider subcontractors needing to connect to servers in a particular department.
Ford has 181,000 employees as of 2013 (http://en.wikipedia.org/wiki/Ford_Motor_Company).
That's very roughly 92 publicly routable IP addresses per employee.
I highly doubt they need that many.
10/8 is off limits, but there are a bunch of /8 blocks which could likely be reclaimed if we really needed to, including:
- About half a dozen which were allocated to the US military in the early 1990s, most of which aren't even publicly advertised at all
- 44/8, reserved for amateur radio
- A number of other /8 blocks owned by corporations, which could potentially sell or return chunks of them if properly convinced