When will we reach the state of more of less stable cryptocurrencies or it is in their nature and will never end?
Because of the decentralized nature of the majority of cryptocurrency out there, the volatility will always be in the hands of the user. Early adopters and whales are able to control most markets by posting buy and sell walls and flood or strip the market with coins/fiat...
The only way to stabilize the value of any kind of crypto is to offer centralized solutions, which can easily be perceived as defeating the purpose of cryptocurrency, but honestly, that's the direction that I see digital currency turning to. As more and more larger companies adapt to digital currency, they'll undoubtedly focus on creating a currency that will only slightly fluctuate in value, but as it currently stands now, as long as their are open exchanges for converting a certain crypto to fiat and other crypto currencies, the volatility will always trail closely behind.
The prices will get more stable when the prices are really expensive...so expensive that it would take a lot of money to get rid of a 1 BTC wall.
Doubtful. We saw what happened last week, as the prices stayed above $15,000. I don't know about you, but that's a lot more expensive than it was just a few short months ago at under $10,000, and MUCH more expensive than last year's (2016) closing prices of under $1,000 per. The value of Bitcoin won't stabilize the volatility as long as there is a demand for it.