You can think about other coin. Beside bitcoin, altcoin is now having it own position in the market. And I hope that it will replace bitcoin and become the best coin ever
What altcoin you hoping to replace bitcoin? You don't say the name but only saying altcoin, Say the name and get your answer whether that coin is worth investing in or not.In my opinion, It is not late to invest in cryptocurrency now. Everybody knows that in the next years, It's price will rise more and more. So, I think this is really a good chance to invest in this area now. I will do the same 
Investing in which coin? That's what OP is asking, OP wants to know what is the next big thing 
You should ask the OP if they already own 1 bitcoin or not? The first step is to hodl a bitcoin and then think about other coins.