If you use blockchain it is. Blockchain is already worked on insurance right now, there are companies who are trying to insure stuff on blockchain to make it more forever there type deal and for that to happen you need the underlying contract to be agreed by both parties and exist in blockchain. Now, if you take that blockchain technology into insuring crypto you can make it happen however insuring crypto assets would require a lot more details then the regular "life" or "house" insurance type of deals because it is harder to calculate the underlying risks.
The premiums must be really hard. The easier method is insuring crypto platforms. Such as coinbase, blockchain.com, bitmain and all those crypto related stuff could be insured instead of crypto itself. Much easier method and still insuring in crypto world.
Dunno why someone above was afraid of promoting anything as I don't think it was.
I came across the service called Cryptoins that is actually designed for providing such services and saving our holy grail Coinbase and Bittrex exchanges. Haven't heard on anything of that kind yet.
As for the companies that are into insurance they may not be not successful with the implementation of this idea as for at least another couple of years: the crypto is only starting to gain its credit amongst legislation systems of the world so it will have lotta improvements + all the process must surely be much more complicated to make assets- insurance Blockchain-based thing work.