The cryptography used in Bitcoin is secure. For now. In the future, a quantum computer could take over the network and basically render it useless. Some researchers suggest fully functional quantum computers could be 15-20 years away, but due to advances in technology this could be sooner.
US, UK accelerate quantum computing programs after China breakthrough.
Coin Telegraph
Quantum resistant blockchains already exist One example is CellFrame. It could also be possible for the Bitcoin mining community to run a a quantum resistant protocol over the network in order to make it secure.
It is good to keep an eye on these developments even if the risks are long term.