If new demand is "0" then the value of bitcoin may be "0" and it will be difficult to consider it as an investment or currency.
Again, that's true for everything. If there's no demand for a thing, it has no value.
even if there is no new investors.. the current community might still see value in its utility.
its not a scenario of bitcoin drops to zero if no one new jumps in.. its already an active community of people using it.
EG doe fiat currencies go to zero if their net import/export shows they have less imports than exports. or the opposite.. no
because the currency continues to function if all currency is just stirred around domestically without imports/exports happening.
..
if there was no demand at all. even from current users. first you will see the hashrate drop because miners will give up. the remaining miners will get more reward. which might then re-energise some demand as they can get more reward meaning get more incomes while the price is not yet dropped too far.
then this may cause the price to drop due to those sells. and yes eventually it could drop more and more if the desire fades..
but bitcoin has more function and utility than just "hoarding". its actually a useful currency in of itself. its function is not to just be a bridge to fiat. it can be a function currency without having to ever return to fiat. i personally have coins from 2012 and in that decade most of my transactions have not been back to fiat. but buying goods and services in btc.
i have also used btc to do other practical things unrelated to fiat too