The graph of bitcoins will depend on the law of demand and supply as if demand gets higher then it will directly help in taking price higher as we know that the supply of bitcoin is limited and it will be limited even in future but there is no limit for demand so you can expect much high price in future.

That is true, as long as bitcoin is not banned worldwide people will still use it without getting into trouble, however some jurisdictions like in Russia and Argentina severely restrict or ban foreign currencies, and in others like in Thailand limit the licensing of certain entities such as Bitcoin exchanges, which means even if you manage to use bitcoin in those countries and exchange it to fiat you will be breaking the law, and imagine if that was worldwide it will be a big hit to the knee for the bitcoin.

In fact, there is a limit for demand but we have not touched it yet, there are several limits for demand, like the number of people on the planet, the number of business, or the number of fiat circulating in the world, so there is a limit for demand too.

NO one can say for sure what will happen in future but if some better coin develop ,then it can replace bitcoin and bitcoin would be dead.Technology has very short life and with time it keep changing.Bitcoin is also a technology and it won't remain forever without change or improvement.

In the mean time, Bitcoin is the most popular Cryptocurrency. We all know that through time everything fades and I think Bitcoin will die in the following reasons.

If a natural phenomenon happens, causing all countries to be in the state of calamity where 80% of worlds telecommunications will be destroyed. Bitcoin is using the internet as it's highway, the run will stop when the runway is destroyed.

Conflicts between nations that will result in war. Through advanced weaponry, massive destruction will happen if a world war occurs causing billions of people to die. Bitcoin will die if it has no user.

A better Cryptocurrency will born. We all know that bitcoin has many competitive rivals. Bitcoin will lost its value if people will turn to another Cryptocurrency.

I don't think that I, as a user, matter at all in the bitcoin world. The whole thing can go on without me and you. So is the bitcoin's life. The ones that matter the most are the whales. If they team up and dump the whole market and move to a different coin, then we're all doomed. The only thing we can do is follow the crowd and sell our coins. This is the exact reason why people panic sell. They think that whales are selling and so they also should.

Although we are the most important factor, the users, as an individual we don't matter that much. We matter as a whole.

Whether they decide to accept it or not it's irrelevant for Bitcoin's existence. There are many other countries people of which will continue to use BTC. Negative attitude to Bitcoin from any government will result only their citizens to suffer from it, all the other people will be okay and bitcoin will definitely not die.

Even people do not use Bitcoin as long as there is someone dedicated to mine the network, Bitcoin will not die.  To kill Bitcoin we need to stop the miners, transaction then will be left unconfirmed and the network will not move and stay idle.  With this, blockchain not moving will means Bitcoin had die.

A problem is that if any of those two countries banned bitcoin is that since the two of them are so influential in the world, it could happen they begin to push for a world wide ban on bitcoin and that will be really troublesome for most of us.

There are too many scenarios in which bitcoin or any valuable asset could die for that matter.  I think right now the biggest threat to bitcoin is bitmain.