2018 might be a good year for some of the major altcoins, but I have my doubts about the performance of Bitcoin. Two of the major things Bitcoin needs to address is transaction speeds and fees. I have read articles about many businesses that have stopped accepting Bitcoin because of how volitile the price is on a minute-by-minute basis.
If you want to hear my opinion, I don't believe in that thing. Yes, I definitely believe in volatility, it exists for sure, but it is not the primary reason why many businesses stopped accepting cryptocurrencies. First of all, how many of them have actually been accepting Bitcoin or some other coin? I only know about Steam and Microsoft, though the latter seems to be still accepting Bitcoin at their site for some digital services they offer. All others have been accepting fiat, and the volatility thing didn't affect them in any degree as it was not their concern. It is a matter for payment processors and gateways, and believe me, they know how to tackle it.
Further, the true reason why businesses drop their support for Bitcoin (and other such currencies) is that people are not willing to spend their coins. For most of us crypto is an asset with which we earn money (dollars, euro, etc). It is our financial capital, and spending it on trivial things would be equal to wasting it.