That's somewhere around my cut off date too, but not in terms of gains. I don't believe 2020 is enough time for the gains some people are dreaming of. I do think we'll have a much clearer idea of what Bitcoin's fate will be by then.
If there isn't any scaling and even more centralisation then I'll be walking away. If it can't evolve then something else will.
I agree that 2020 is too short for bitcoin to increase in price dramatically. I think it will take another two decade, that is if the current problem of Bitcoin is solved. If not then I only see the current Bitcoin supporter moving to another cryptocurrency thus making all the prediction invalid.
As for Bitcoin fate, let us just wait for your time frame. I do not have an idea on when will the fate of bitcoin unfold.
What current problem? The scaling problem? Because that will never be fully solved, just like the internet scaling problem is always a problem, so in itself is not a problem, its just a never ending process.
If by 2027 21 BTC holders aren't rich it will be a disappointment. At least 1 million USD per 21 BTC holder should be guaranteed.
Of course there are always going to be issues, but if it can't get past the current one which is eminently solvable then it won't be able to manage anything else in the future. It's something of a canary in the coalmine type of scenario.