I am a player that likes to evolve and have long last era gameplays. This idea kind be difficult maybe, but it consists in let to change the affinity in the last era to any culture. Why? in some gameplays you stay without a real advantage with an affinity in the last era. And can be interesting to see a Chinese expansionist, Cuban scientist, Brazilian builder. etc. any combination. changing the affinity can make a more interactive game in last era and keep evolving in some way. 

I also think that if these can be done, it should be very expensive because the idea is not to change it every 10 turn, it should have a minimum of turns and be expensive. 

I hope you keep in mind the idea, and i would like to know what other players think. 

if you got suggestion let them know.