If you need to know that there will be a registry
  for each new gTLD, then I'm willing to run any of
  them that cannot otherwise find a home.

The new gTLD's are all ultimately going to be shared. There's going to be
a crossbar effect where registries and gTLDs are not mapped one to one; any
registry will be able, if willing, to register names in any of the new gTLDs.