Endless discussion: is Bitcoin a bubble?

According to pundits, Bitcoin will either go to zero or to a million USD. But a Harvard professor believes it will collapse at some poit.
Bitcoin's future is notoriously hard to predict. The experts either believe it will either to the moon or collapse. The last one to join the pack of those foreseeing the debacle of Bitcoin is Kenneth Rogoff, professor of economics at Harvard University.

Ken Rogoff is a professor of public policy and economics at Harvard University. He holds an impresive academic background, including degrees from Yale University and MIT. He served as the chief economist of the IMF from 2001-03. With such a background, it is impossible that his views on Bitcoin attract a lot of buzz.
Dim Views on Bitcoin
as he stated in apost in the Guardian:
"Is the cryptocurrency Bitcoin the biggest bubble in the world today, or a great investment bet on the cutting edge of new-age financial technology? My best guess is that in the long run, the technology will thrive, but that the price of Bitcoin will collapse."
As he acknowledges that some governments like Japan are in the lead in regulating virtual coins, he endoses it to a desire to become the major leader of fintech. He considers most governments to ignore Bitcoin while shows small adoption for anonymous transactions; but they will act against it once cryptos becomes more widely used.
"The long history of currency tells us that what the private sector innovates, the state eventually regulates and appropriates. I have no idea where Bitcoin’s price will go over the next couple years, but there is no reason to expect virtual currency to avoid a similar fate."

Ken Rogoff's arguments on Bitcoin's likely collapse seem to replicate Jamie Dimon's views (JP Morgan CEO) - that governments will not let Bitcoin to become successful and big and will coerce Bitcoin users into quitting it.
When asked over the government's ability to shut down a platform that is virtual and knows no borders, Jamie added that governments could threaten Bitcoin users with jail sentences. It is interesting to notice that all the prophesies about Bitcoin's skepticals come from characters within the establishment, whose very future cryptocoins threatens.
Eventually...
ken Rogoff has predicted that Bitcoin will collapse, but within no time frame for this to happen. Therefore it is impossible for him to be proven wrong, even if eventually Bitcoin becomes worth a million, as it might still collapse after all. Analysts who work in the real world (big difference to theoreticians) need to make time specific predictions. Obviously there is a BIG difference between an asset's price doubling in three years or doubling in thirty years.