the current distributed nature of all crypto-currency including bitcoin is probably a threat on how banking system operates. current banking system usually is a centralized system, where all trust is placed on the banking institution. for this reason itself, crypto currency model will not be adpoted and accepted by banks, however, its in their best interest to regulate it though.

i think, in the future, in some way, the currency will shift towards being digital currency. in any case, most of the transaction we do are virtual any ways, i.e. using cards.

The very nature of crypt-currencies reflects that we should not seek for a bank/government-level regulation so, I think the answer is yes; the crypt-currencies will be widely used but waiting for banks to support it? I think it's kind of against the philosophy of this new currency.

I think it can not be accepted unless it is regulated by any trusted body. Otherwise it may affect the economy of any country as well common people may be bankrupted. It's my assumption nothing else.

It's very difficult to pinpoint what could lead to the adoption of the Cryptos. It's a completely unfettered market and that's exactly what makes it interesting and different than the regular currency. So, to begin with, if more merchants are willing to accept the transactions in Cryptos, sure! It'd be all over, in no time. Also, the Govt. has to give a go-ahead. But it's quite unlikely that the regular currency would be replaced anytime soon. I'd resonate with the answer by Rupak above, that it'd definitely shift towards Digital currency but adoption of Cryptos, doesn't seem to be happening anytime soon. They're too volatile to be accepted as a stable currency!

The widespread adoption of cryptocurrencies by citizens pose a threat for banks and governments. It will be hard to introduce legislation / regulation and keep the original spirit of a decentralized peer-to-peer model.

Here is my take of this issue. Satoshi Nakamoto white paper on Bitcoin is premised on the philosophy of founding an alternative currency to fiat. Fiat being money regulated and centralised under the control of the state, the opposite of cryptocurrency as designed on the principle of doing away with the state control, state involvement, elimination of third parties like banking institutions.

Therefore, the whole notion of state involvement and regulation is simply a digression and blatant violation of the basic philosophy for which cryptocurrencies were founded. You and I know it well that the birth of Bitcoin came as a response to the 2008 financial meltdown that started in the United States after the structural collective failure of the banking and the federal system manipulation of currencies.The original idea was thus to introduce another currency designed by the people, for the people within the people - Free from the state in any form, be it regulation or otherwise.

However, my take is that, such ultimate status of absolute freedom of cryptocurrencies from statutory role would come in states.

Stage 1: Wider usage of cryptocurrencies up to a certain critical mass in the world to warrant respect and recognition from all institutions of state, private and civil society to a level almost where cryptos are accepted by many merchants as a means of transaction for services and products in circulation in society. At this stage, you do not need permission from government or banks. It is a people-to-people or peer-to-peers exchange mechanism that has to grow within free people and free institutions of the world. Obviously, whenever the state is left out of a major and phenomenal transformative system like this will invite confrontation with the state (with the law) at some point because, inherently, the role of the state is by nature that of regulating ives of its citizens, invited or uninvited.

Stage 2: The Accommodation of local and International payment Systems in the cryptocurrency ecosystem. This is now the stage that starts with traditional banks exchanging fiat for crypto and vice versa. We have seen a lot happening at this level. Some banks have openly liberalised transaction almost to a point of having dualistic currencies (fiat and crypto) running parallel to each other, even though some crypto have not been accepted as legal tenders. Afraid of loosing clients, some banks have started to accept and accommodate their clients using cryptocurrencies, and by extension, payment systems such as SWITCH, VISA, MASTERCARD etc have also no choice, but to jump on the blockchain system of transaction. Otherwise history can judge them harshly. At this stage, the noise of confrontation with the state and the law will even be more noisier as the concern of the state becoming more and more marginalised, especially now, by institutions such as banks and international order that control global economy would mean a threat to sovereignty of nations. So expect more noise from the state and this is why countries like China and and a few more are juggling with coming up with their own centralised digital currencies and banning cryptocurrencies to retain statehood and sovereignty of nations and also eliminate competition with their own self-designed digital assets.So at this stage, expect the confrontation to intensify and calls for regulation to grow even higher - a noise that will be made more by government and financial institutions in fear of being retributed by the state. But all this, is just the fear of the power of control being now unorthodoxically taken over by the people - the free spirit of the ordinary citizens of the world. This is a revolution based on the disruptive transformation and you do not need to curry over the garbage of the old paradigm into the new order. Regulation is not needed because cryptocurrencies and the blockchain technology is redefining the role of what the state should and should not do. I for one, am of the view that the role of the state in playing any function in monitory activities are numbered.

Stage 3: Weather of the State. Consolidation of blockchain decentralised management. The New beauty of the world will now be defined on an all-inclusive global economy where all transnational activities whether in the financial sector, legal, trade, citizen control, elections etc are can be entered and verified in a distributed manner free from corruption and control and manipulation by any one single authority.Using the Blockchain technology, the power and will of the free citizens of the world will have taken over and maybe a new United Nations Agency will need to be formed to oversee the rollout of blockchain governance and to ensure that all designated (ratified) countries of the world are compliant and respect the basic principles of blockchain-based operations without interference.At this stage, the world will be having a single currency, single regulatory framework of currency. When we are here, the principles and philosophy of Satoshi Nakamoto will have prevailed and therefore the world should be prepared for a long battle to rich this point.

Whether than universal currency will be Bitcoin still or something else it does not matter. Bitcoin is only a currency, but what we should embrace is the principle of approach to ultimate freedom of the world citizens from being confined by their governments.