Thanks for entering a vote on a comment and for kick-starting the discussion!

You raise good points, and I agree with most - especially the part about Susan Rice. I just looked at the list again for today's updates from predictit. I didn't do a line by line comparison, but three things that jump out at me are that (i) Susan Rice moved from $0.22 to $0.32 and that (ii) Hillary Clinton is now ranked at #9 with a price of $0.02. Given your comment, I'm sorry to say that (iii) Hillary's rise bumps Tulsi Gabbard out of the top-10.

An interesting aside is that earlier in the week I heard a TV analyst say they were expecting an announcement this week, but according to this contract predictit is favoring next week, August 9 through August 15. I started following it last week, and predictit has been consistent on that point. Today on TV, I heard a different TV analyst suggest that an announcement this week is unlikely. During the 2016 election, predictit was hours ahead of the media on election night, and if next week turns out to be right for Biden's running-mate announcement, then they seem to be ahead again.