Currenty, bitcoin has fallen by more than 2 times compared to last year's highs. Will it return to them and if so how soon? Unknown. We only know that you need to constantly buy more bitcoin.
And it doesn't mean a thing. Instead of treating the ATH as something average, you should look at it as an abnormality. In reality BTC was never really worth 20k USD, it only traded at that price due to limited supply on exchanges and a huge number of new investors coming in. All they wanted was to earn a few dollars and sell it all, that's why it quickly crashed back to where it is now. It's still a great price though.
To make it short, we'll be above 10k USD in a few months and will break the ATH within a year. I also expect a huge acceptance and regulation by 2020.