I think if the price doubles some campaign will still pay the same rates , I was in a campaign before and at that time the price increased around 20% and when people asked if they were going to reduce the rate they said that they are paying bitcoins so their members shouldn't think about the USD value
but at that time most of the campaigns reduced their rates
now when we are talking about crazy prices like you mentioned the campaigns will definitely reduce their rates , cause advertising on TV would be better I guess if they will keep paying at today's rates