If it was any other asset, I would have still had my doubts but with bitcoin it's quite an achievable target to hit $1 million.
I won't speculate any date because that's something we cannot predict so easily but given the amount of time it has taken to reach $100k I guess it will at least take 8-10 years down the line.
Just imagine the amount of money in marketcap that would be needed to reach such a price.

Anything is impossible on the market.
And with BTC - you are sure of it if you understand it.
Just let the market do its magic the cycles of BTC change themselves naturally.