Another threat to Bitcoin. Quantum computing:
An analysis of the impact quantum computers might have on the Bitcoin blockchain
Regarding the threat from a quantum computer, the public key is directly obtainable from the address. Since all transactions in Bitcoin are public, anyone can obtain the public key from any p2pk address. A quantum computer running Shor’s algorithm could then be used to derive the private key from this address. This would allow an adversary who has a quantum computer to spend the coins that the address had.
A friend who was lured out of early retirement after multiple successful startups claims he has held a million (IIRC) qubit chip in his hand. He told me about this in January of 2020 when he was seeking funding to take it commercial. The last time I talked to him about this COVID had halted his funding quest.
Whether it is Google, IBM, Microsoft, other big names, or any number of startups who want a piece of the pie quantum computing is going shake up a lot of things. Bitcoin, at least as we know it, will probably be an early casualty but it will be far from the only one.