The network implementation as is, in particular the delay between blocks, means that the network cannot work on a large scale system.  The network will lose coherency and forks will develop as nodes become separated by distances approaching 10 light minutes.  For reference, sometimes Mars is further away from the Earth than that.  A series of nested chains with increasing delta T targets and difficulties will be required to have a coherent network for interplanetary or interstellar communities.  Lets think ahead folks