Bitcoin can be used for whatever purpose people find it suitable for.
Of course. People can do whatever they want.
But if the restrictions on transactions don't get changed before a possible "mass adoption" it can't be used as currency effectively anymore.
And this will make it unusable as a currency as well as an investment (or gold 2.0), because it's value as a speculation object / investment stems first and foremost from it's possibility to be transfered quickly and cheap.
So, if the rules get adapted (asap), there is a huge chance, that it can be used as either a currency or gold 2.0, or whatever you want it to be, in the future.
If they don't get adapted, there is a huge chance, that it won't be anything of these but another promising invention going down.
If bitcoin fails becaus of it's restrictions and uncomfortability, people won't have any trust in decentralized cryptocurrencies. And in the end it is not about any of us who mined bitcoins in the beginning because it seemed like a brilliant, promising idea. The decision will be made by the "common man". Bitcoin has the opportunity to prove to the people, that decentralization can work, that it doesn't have to be managed by the big brother.