If you need Nathan to make things work out mechanically, I can probably manage to bring him back, but it seems like a reasonably well-balanced party as it stands: 3 fighty types, 1 arcane caster, 1 divine caster, and a bard to give a little boost in both the arcane and heal-y departments. And I'm not sure Nathan's anything but waiting to be squished at this level, anyway.
I suppose I could also try officially retiring him to try out my not-quite-mentally-stable wood oracle, but that whole 'building whole cloth at upper levels' thing might break me.