Bitcoin won't go up forever. By it's own definition that it is a currency, the end game is for bitcoin to have a stable price once adoption reaches equilibrium. It could be a very high price but not a forever rising price. No point predicting what it will be, pretty much impossible to predict.
yeah, for us simple bitcoiners, it will really hard for us to predict of there would be a final price for bitcoin, and I would agree that not all the time bitcoin price will rise. It will also dump some of the time. Just like what happen for the last time.