Diuble spend is detected when a longer chain is published to contest the currently accepted chain with orphan depth of more than 5-6. This is huge deal and will

Diuble spend is detected when a longer chain is published to contest the currently accepted chain with orphan depth of more than 5-6. This is huge deal and will decimate butcoin valuation for sure, but just as with acceptance of segwit and hardforks around protocol bugs in the past - there can be agreement made to deploy a version of bitcoin software to hardcode which chain is valid. Not saying this is easy but when the project is attacked like that, there will be some action.