Bitcoin and other crypto-assets have long divided traditional economists and bankers with some warning over their instability and others praising their ingenuity.

The bitcoin price rebound so far this year has caused some to change sides, though many continue to warn bitcoin and other cryptocurrencies will be a mere flash in the pan.

Earlier this year, Christine Lagarde, who has just been nominated to replace Mario Draghi as president of the European Central Bank (ECB), warned that cryptocurrencies are "shaking the system"—something that could signal a change in the ECB's approach to bitcoin and crypto and potentially spur adoption.

International Monetary Fund managing director Christine Lagarde has been nominated to take over from European Central Bank boss Mario Draghi—and her attitude towards bitcoin and cryptocurrencies could be important.

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"I think the role of the disruptors and anything that is using distributed ledger technology, whether you call it crypto, assets, currencies, or whatever ... that is clearly shaking the system," the 63-year-old Lagarde told CNBC in April.

"We don't want to shake the system so much that we would lose the stability that is needed," she added.

Those comments earlier this year follow an interview with Lagarde in 2017 where she warned the power of cryptocurrencies and the underlying blockchain technology should not be dismissed.