What do you see in the future for bitcoin with quantum computing?
1. No working quantum computer has been built yet.
2. A Quantum computer can reverse a public key. i.e calculate private key from public key. That is the end of the security of BTC
3. Quantum computers have massive computational power so they could get more than 51% of computational power of BTC network easily which may lead to spent same BTC twice. i.e breakdown of the system.
POS can secure blockchain only from 3rd fact in the list.
Will everything convert to a Proof of Stake system? Thoughts?
However even POS is vulnerable to quantum computers. See here -
https://bitcoinmagazine.com/articles/quantum-computing-and-building-resistance-proof-stake/Conclusion
If someone build a quantum computer it will be the end of BTC. Only Quantum proof cryptography based cryptocurrencies will be safe.