Well it might be anything. Big bank willing to invest, country willing to hold small part of its reserves in BTC (f.e. Malta which is soo positive to crypto) , Founds willing to invest in BTC, MT gox case solved by burning remaining BTC and manny more. It might not be something that everyone know it'll happend. Funny thing is that we might see it firstly on chart and then (after all insiders bought) as a news.
if bitcoin starts rising only because of things you mentioned such as banks investing in it or countries,... then it means bitcoin has already failed and will not survive for long. the fact is bitcoin has been rising (and will do in the future) only because it doesn't need these things. because bitcoin as a decentralized currency that nobody controls already creates enough incentive for people all around the world to want to own some of it and benefit from using it. the rest are only additional pushes on an already rising price.