An alternative version of these type of funds could be to deal with capex on mining hardware and/or r&d on new technologies for mining/semiconductors.  In this way, rather than the fund being a trading vehicle for bitcoin only, it would be able to identify companies which have some influence in the way bitcoins are generated.  For example, AMD would be an obvious candidate, but other companies working in similar promising areas would be available.  This could help to legitimatize the fund since it would have traditional instruments which would 'benefit in the rise of bitcoin'.