Agree 100% with Neuro's statement above.
Sun Tzu Wu
Actually, now that I think about it, the SP policy change won't stop the sell-city exploit, it'll encourage it!
Scenario: Playing France, you go ICS early on and crank out a bajillion cities. You are forced to grab a few policies early, but then your cities outgrow your SP and you never buy another policy because they are so expensive. Then, right when you build Cristo, you sell everything but capital and puppets, and coast to a win!