I guess there will not be any point that bitcoin will stop moving in its price levels. I believe it will keep on moving forward/ fluctuate at least for next 200 years. All the above we never need to sell our bitcoins, we are going to have our local shops accepting bitcoins so we can use bitcoins instead of converting them into fiats.
If the statement you said at the end becomes true then none of us will need to sell our coins as we will be able to use them directly as we do use fiat in stores and shops for buying things and many other places, but maybe if we had the price dropping sometime then maybe we would think of selling them as they would have the same value in fiat after selling.