I want a government system with more realism & complexity, so I doubt I'll ever seen any of my ideas come to fruition.
In Civ4, it's possible to drastically change the entire nation's government every 5 years, which is completely unrealistic.
Aside from the unnatural flexibility to frequently change religions and civics, it's impossible to expect any major social or governmental changes to take immediate effect and grant the nation its full benefits.
Take Emancipation in the United States for example: Slavery was abolished over 140 years ago, but it wasn't until just 40 years ago racial segregation ended. Even still, there is arguably a long way to go before all "artifacts" of slavery are removed from the government and culture.
Whatever civics and governments are used in Civ5, I think they should be subdivided into different time-dependent levels. Each level would get progressively better so each civic gets better over time. (This mimics the nation accepting and dealing with the changes over time.)
The lowest level would be much like the "Anarchy" we have now, except it wouldn't completely grind the entire nation to a halt when adopted. This initial Anarchy would impose a certain amount of applicable penalties with no benefits and would last only a few turns.
As time went on the level would increase, and with each level there would come fewer penalties and greater benefits.
The opposite would happen when not in a particular civic:
For example, if you were in Caste System for 100 turns and switched out to Slavery for 10 turns, then when you returned to Caste System, you would pick up at whatever level 90-turns put you in. (If this wasn't balanced, I'm sure a percentage penalty could be imposed to the turn counter of whatever civic you're leaving).
-- my 2
