It actually depends if everyone is still using bitcoins and we do not need to think about how long bitcoins will survive, Even within just a year, You can be rich if you really focus on earning this coins and working hard everyday.
I guess not. The mount of energy to maintain the network is huge. And give it 20 years or even less and we will see this model is not sustainable anymore Which willl when a new kind of more innovative version of bitcoin will overthrow bitcoin as we know it today.