1) The sacred Bitcoin Protocol: I think the current proposed HF from 1mb to 2mb wont make or break anything. But, it'll set a precedent that bitcoin protocol can be changed according to the demand of a cheering crowd. In future, there may be a cheering crowd to raise 21m supply cap. Question is what we do then?

2) Segwit: Malleability is already fixed. Segwit does not fix it further. Segwit is aimed to create space within 1mb block size and creating scopes from Sidechains & Lightning Network. But, Segwit is complicated. It might become a disaster like The DAO. Hence, as Segwit is soft fork, there should always be non-Segwit nodes and applications doing non-Segwit transaction, so that in case of a disaster, a part of the network survives and hence bitcoin.

3) Sidechains + Lightning Network: Secondary layer. No problem.

4) Urgent Hardfork: Very unlikely for robust network like bitcoin.

5) Quantum Computers: FIAT money sitting on banking network is on much more threat than Bitcoin network. We are ~10 billion USD, while they are in trillion. We might sit back and enjoy the show.

7) Corruptible devs: Devs can not enforce anything immediately as a change to the network. They can hold back the existing working system and resist a change. So, dev level corruption is no big threat.

6 & 8 ) Corruptible miners & Corruptible community: Corruption is a relative word. In a way, a part will always be corrupted. But, in reality, only those matter, who have deep skin in the system itself. In reality, community is miners and holders. If there are 1000 corrupted holder holding 0.01 BTC each, then they will have less effect on the network than 10 holders holding 10 BTC each. Because, if, at any point, holders need to decide the winning chain, the coin holding majority will decide which chain will survive by selling the other chain's coin. Individual majority of holders is not important. Now, to serve their own interest, the majority holders wont go against the best health of the bitcoin network, corrupted or not corrupted.

9) Hardfork not fair for long term savers: Already discussed in above points.