A little update on this thread.
The spreadsheet is broken after so much time, so I will try to restart it again.
In the meantime we can see how the BTCE portfolio evolved over the last months:
it interesting that the number of Bitcoins held in the fund is closely following the steepness of the contango.
As the contango steepens the number of Bitcoin held grows, while when the contango is flatter the number of bitcoins decreases.
This hints at the usage of this ETP as a leg in the cash and carry trade.
If the contango grows positive, then speculators will try to sell the futures and buy the spot.
Buying the spot means that they will buy this ETP, hence the amount of BTC held in BTCe Walle will grow.
But doing so, they will also make the curve flatter.
When the curve flat enough, they will close the position and wait for it to become steep again, as keeping the position open has a cost. Closing the position they will end up selling the spot leg of the trade.