You have a good hint on this, and the more and pressing the demand for it, the more the value, which might later be causing the scarcity-induced price hike. It will be insane by then, provided the demand has become bitting at the time, and not what we still see now.
I tell you, if the total supply of Bitcoin is 50 million, the price will stand at the current level, that is what @Ambatman refuses to acknowledge. So, for now, it is not about the scarcity, Bitcoin is still readily available. The natural value attributed for being an asset itself has diven Bitcoin this far.
You made this example so arbitrarily and if you expand it like if Bitcoin has total supply like Ethereum, its price will stand at the current value, it turns to be very wrong. Total supply figure is important but it is not the only decisive factor for value and price of Bitcoin. If it is changed to 2x, 3x, 4x or bigger x, value and price of Bitcoin would be changed a lot and no longer stand at as same figures as now with 21M bitcoins in total supply.