Ethereum will not over take bitcoin. In fact, its a declining platform. Its very complicated to use, even from dapps developers, and has many bugs and glitches.

Moreover, to run code on the ethereum blockchain you have to spend ether and the longer the code, the more ether it costs. At the end of the day it is actually cheaper to run your own code on your own server without using the ethereum.

Furthermore, there are seriious scalability issues. If too much code is put onto the ethereum blockchain, it would take to long to confirm all the states of the smart contracts and apps will stop functioning properly.

There is no need to use ethereum unless you are doing something highly illegal.