:)There are lots of things that could able to make bitcoin die. 1st. No one will use any cryptocurrency 2nd. There would be a new crypto that would replace bitcoin 3rd. No internet 4th. All government would ban it globally. and there are lots to mention but still we know that bitcoin wont die easily.
As many have said before, a ban on bitcoin will only make it illegal but it will not stop people from holding it just look at all the things that are illegal and that people still use, about your second point even if a new crypto appeared that replaced bitcoin that does not mean that bitcoin will stop being used by the people.
If Bitcoin is made illegal its usage will diminish dramatically
It simply doesn't make sense to use something illegal when it has many legal alternatives (e.g. cash is better suited for illegal activities since it in general doesn't leave "fingerprints" on the blockchain). The things that which you refer to and which are still being used when outright banned don't have full substitutes, like, for example, drugs, so drug addicts don't care if the drugs they use are legal or not. Bitcoin is nowhere near that. Indeed, there may be a number of Bitcoin addicts but they are few and far in between