even when attacked from the inside by blockstream/core it just forks and offers two chains. at least one will continue delivering p2p electronic money to the people with low fees. maybe both? we'll see. 
Technologically yes. Completely, Politically, Well sort of. Bitcoin is a technology. Not a company or a specific currency. It's fully decentralized across about 10000 computers worldwide, any one of which can fully restore the entire network. In a way, its very similar to the internet. You can block specific people from using specific websites
but its pretty hard to stop the internet. In other way bitcoin is unstoppable.