I do not think that the price will grow very quickly ! I think that it will grow smoothly and in any case it will overcome the mark of $15,000
It is difficult for a coin to grow smoothly because the market always has a certain cycle. If the ETH price does not increase rapidly, it won't reach $15,000 in next 10 years.
For that, if ETH will launch Etherium 2.0 with improved scalability by sharding and Plasma, limited max supply and masternodes - $15К price will come true.
I don't believe Ethereum will ever hit $15k, this is just a pipe dream. $15k per coin pegs the market cap of Eth at over $1.5 trillion. Bitcoin can surely hit this number, but Eth will have to live in it's shadow. ETH could maybe top out at $3000 USD but not much more than that. I just hope ETH recovers, because honestly it may never recover too. There are a lot of different outcomes for ETH, not all are bullish. The news about the breakthrough in sharding does give me some hope though, I was starting to think sharding was vapor ware.