"But doesn't NANO have a CEO?"
No - but the not-for-profit NANO Foundation does. There is a difference.
The NANO Foundation is a not-for-profit that was established to help facilitate and fund the development of the protocol. It held back approximately 5% of all NANO created to fund initial developments, of which less than 0.2% remains. The protocol has several key members around the globe helping to improve NANO.
While yes, the founder, Colin LeMahieu, is a major contributor to the project being its original key architect, the protocol can nearly be considered complete - all on-going updates and changes are improvements on NANO's code and functionality. The work being theorized, proposed, and updated are contributions from many members in the NANO developer community.
If Colin decided to stop working on the project, there are many many others who will step up and continue building on the Network. Please also note he has NOT made any indication that he intends to stop working on the protocol, and has maintained a very active role in key research on topics that will help the robustness of the network, again with the help of others in the community.
The commitment from outside participants on the network have expanded on that topic. Looking at the Kappture White Paper (page 4, section d.) they state:
d.Code review & maintain ability
Our developers had to be comfortable with the project code following a thorough review, and be comfortable maintaining it, if necessary