Why not add a little spice to next age. CF's always seem to be an issue, no one likes doing diplo, and it has gotten extremely political. So I propose 2 options for next age.
Option 1) Completely remove CF ability next age, except for EOWCF.
Option 2) Incorporate a section in the CF page to add a "Duration" period. Not exactly sure how hard the programming would be, but you could possibly set a Date format for when expiration of CF is. So it would be a mandatory CF until that period so no "Dealbreaks" would actually occur.