$5k price is possible to achieve in future but it will take long time for that and I don't think that many will hold their coins that long as most of them will sell even if it reaches $1k.
I completely agree with you,if and when price reaches magic 1000$ most users would sell most of what they have and it is likely to bring price down again.It will be more difficult to reach a four-digit figure and keep such rate stable for a longer period of time.
I think to achieve the price of $1k it will take long time and don't see it happening in this year, price will boost up only if we find big investors putting their money in bitcoins.