Well i don't think so that the campaigns will lower their rates because these rates are running from many months no matter what is the price of bitcoins . I would say that the rates of campaign per post are universal rates So we will not see any change .
But ive seen some campaign starting to close down maybe they are affected to it and others really lowered their payments because their payments are based on USD and thats totally ok as long as they will continue their campaign and we are still payed.
Well just tell me if bitcoin price hits 100$ the campaign will not higher the rate for Example if btc hits 100$ my campaign will keep the rate of 0.035/week because it is stated in OP that you will earn 0.035/week for your post no matter what is the price of bitcoin if they want to vary the rates then it should be stated in OP we have rights to change the rate of campaign with the increase or decrease of bitcoins price in USD.
But ive seen some campaign starting to close down
Maybe their site is not so interested for bitcoin forum users ? Or maybe they are done here ?
Have you read this ?
UPDATE
We're really satisfied about results of campaign and we want to increase it ! So, I have taken a decision, based on a particular control of messages of everyone.