In Latour’s words, Whitehead replaced the concept of substance with that of subsistence. I appreciate Latour’s insistence on the need for the creation of institutions that encourage and sustain themselves through transformation. Question is, what would such institutions look like?
"The safest general characterization of the European philosophical tradition is that it consists of a series of footnotes to Plato." —Alfred North Whitehead
Footnotes2Plato 
He talks about the ‘ideal’ institution of a university at the end of Gifford 5 (I think), in the Q&A. But what are in mind are not necessarily concrete or situated institutions (this or that church, this or that government), but instituted regimes of truth in and through which many and various people can compose in harmony together, according to the particular veridiction of that regime of truth.
Ah yes, thanks for putting this back into the context of the Modes of Existence project. That is helpful.
Having been a member of several robust institutions–the RC Church, US Marines, Union Bank—I understand their dynamic relationalities. In an executive position in the latter two I saw that a special set of skills is requisite to fulfill one’s dual responsibilities—achieving a mission but promoting the flourishing of members in many aspects of their lives. Each institution has its customs or habits,which are not everlastingly static,but evolve. We must allow for innovative spontaneity yet meld such into harmony with traditional ways. This requires an internal justice,a form of love for both ideas and persons(really collections of ideas). Modern stress on atomic individualism causes us to forget we are born into groups—family,village,church,nation-state—and form others which move toward institutionalization( Sartre). Students need to be taught more about group activity,but not merely at a superficial sociological level but in more philosophical and theological depth. Latour alerts us to this,but much more needs articulation. See Sartre on groupe-en-fusion, Peirce on habits, Tillich on justice and the polarity of individuation & participation.—–Chuck