The reasonable number would be around 5 to 10 trillion dollars in market cap, those are the highest numbers in most of the worlds biggest stock markets cap so it would make sense if the crypto currency matches the stock market one day. I am not saying it will go there soon or it will ever reach there or even will not pass that, anything could happen in crypto world and I wouldn't be shocked.

Nevertheless, those numbers are reasonable and not supernatural, they could be achieved and nobody will say it deserves to be higher or lower since it is at what it suppose to be. Which means one bitcoin should worth around 250 thousand dollars to 500 thousand dollars, will it happen this time? I don't think so but its not a race so we should be reaching there one day or another.