Bitcoin seems to be the past and Ethereum the future.
The question is : when BTC will worth almost zero? Next year? In 2 years?

At the time when you wee posting this thread bitcoin was at its best level of development but after that it dropped down to bottom and then with the help of developers it came back but now it is not in the stage that it will compete bitcoin. Bitcoin now gone more farther from etherum on the path of success and Ethereum do not look like it will once again stand in competition with bitcoin. So the future is bitcoin and will be it all the time.