if bitcoin wont exists, which coin you think can become the main one and why?

[dothebeats]

None since bitcoin set as the precedent of all cryptocurrencies existing today. No one as genius as Satoshi Nakamoto would have thought of creating a digital currency like what bitcoin is since most people would still just rely on cash and would be fine in using traditional banking methods. If not for bitcoin's eventual worldwide success, alts such as litecoin, ethereum and the likes wouldn't even be thought of being created.

[hunnykaushal]

This year, there are many good projects in row. Some of them are

1. Nucleus Vision
2. Arcblock
3. Cybermiles
4. Travelflex

Before you invest , Do your own research.

All the best

[Petersha]

I don't think there is any project near to bitcoin till yet.

In case it happens in next few years then there are many interesting projects coming in 2018

one of them is  Cardstack

you can look on this project and don't consider it as investment suggestion. Do your own research before you invest.

All the best