As for the value of 1 BTC, it's value fluctuates if you operate on a base currency which is not BTC, but that is the same for any currency exchange.
(I am suggesting currency, though I also understand that BTC may not be unanimously agreed on as a currency— but in El Salvador's case it is)
Yes but also, even though 1 BTC will always be worth 1 BTC, the amount of work it buys you won't be the same, as with any currency. In theory, you can also store USD for an infinite amount of time (assuming you exchange the paper for new paper when it decays), but it, too, won't hold its value.
This is actually not true, as 1 USD does not equal a static percentage of all USD. If you look at the stock-to-flow of storing value in USD compared to Bitcoin or even Gold, it's immediately apparent that USD or central bank backed fiat currency is an exceptionally inefficient way to store value as it's being debased at alarming rates.
This is why $1000 was worth way more in 1980 than it is today.
Edit Note: I actually just re-read your comment and realised I misread. I read store value for an infinite amount of time
EDIT: corrected public key, I had written "public/private" for some reason.
This does not remove Bitcoin from the network, just because it is never spent.
> The developers/community may very well decide to change the total amount of bitcoins available in the future
Actually it's not possible. You can fork the network if you get some level of consensus from developers, miners and node runners (not to mention a community that is willing to accept their value be debased) and increase the supply, but then by definition your coin is not on the Bitcoin chain, it is on your new forked chain.