I don't believe that the world will become so "digitized" as you describe it.What about the poor countries in the third world?Do you think they will become "digitized"?However,to answer your question about what comes after bitcoin.My answer is...nothing. 
The blockchain technology might be adopted in various industries,but all cryptocurrencies will become obsolete.
The blockchain technology might be adopted in various industries,but all cryptocurrencies will become obsolete.
There are always ways to implement things once government legalized cryptocurrency. To digitized the world is unrealistic due to the fact that there are still things that technology cannot do. In case it will, I think the world in the future is more advance than we think today.