If you hold steem power, you receive interest on your steem power, so the number of steem power you have grows over time. That's not to say that the dollar value of your steem power will increase or not, which is a lot more complicated of a question.
Well he, along with @ned are the two creators of steemit.
How much would it cost to buy as much steem power as they have?
ALL THE MONEY
Combined, @ned, @dan, and @dantheman have about $20 million worth of Steem Power.
Over time, if this site remains popular, will their steem power drop or grow?
If you hold steem power, you receive interest on your steem power, so the number of steem power you have grows over time. That's not to say that the dollar value of your steem power will increase or not, which is a lot more complicated of a question.