If you can do better, please share :P Unfortunately, I just don't have the time.
Besides, the only conclusion that can be drawn at this time is that this is going to be a one of the largest kickstarter-style funding efforts ever.
The problem with your original calculation, is you're assuming the rate is constant, which it may be, roughly, for day 3 through day 27, however in these campaigns there's always an uptick right before the deadline. Really, it's that uptick that you want to estimate, based on previous campaigns.
I don't think kickstarter or indigogo release this kind of data though, unfortunately.
http://www.kickstarter.com/blog/shortening-the-maximum-proje...
This is the data from the largest kickstarter "Pebble: E-Paper Watch for iPhone and Android":
http://www.kicktraq.com/projects/597507018/pebble-e-paper-wa...
If you notice, the earliest part of the campaign has nearly the highest RoC. Towards the middle, it kind of flattens out. And, as you mentioned, towards the end (the uptick) the RoC resembles that of the beginning of the campaign.
If everything remained constant for the next 27 days, that "uptick" would have to be >$10 million dollars on that last 3 days.
Still, they will beat the largest kickstarter campaign ($10 million).