That is something that nobody knows and is almost impossible to predict. I think that when bitcoin is going to die that we are going to notice it before it actually is going to happen but right now I do not notice a thing.
Bitcoin will survive for at least two decades, and it will not die soon, as more people and businesses are entering into it which will take bitcoin to higher level.
At max it can survive a few decades. By then it will become obsolute.
I expect by then we will see a new kind of virtual currency which will take over. Something not mineable.
The only threat to bitcoin is it might get replaced by new and innovative currency in future, but till bitcoin is doing well I don't think we have to worry about anything.
I think no, many decentralize coin has been made but many of them failed because bitcoin is well establish and very popular to people globally and new alts cannot get the trust easily since many altcoins are died easily or what you called scam thats why those new alts didnt get more support on investors unlike bitcoin we cam easily trust because it is good and surely we can earn if we stake with it.
Countries are trying to adjust their budget to the new era,the thing is will they be ready to control the financial problems,Greece,Italy,Spain,Portugal ,these and more others countries are being supported by euro.
One thing is sure if the governments dont control their wages we will see a deep crisis and yes bitcoin will reach amazing numbers ,since people will try to save their savings before goverments frozen their accounts has had already happened before.