A bitcoin is only worth what someone is willing to pay for it. No more and no less.
Scarcity does not cause use something to be valuable. Buggy whips and old iPhones, for example, are not worth more money ever year even though they become more scarce every year.
Bitcoin has zero utility outside of the ability to transfer it to someone else for some other value.
At this point, it is not easy for your average person to purchase normal goods with bitcoin. Is it cheaper to use? If you talk to someone who uses credit cards and tell them it is cheaper to use bitcoin, they will not agree. Credit cards offer cash back and rewards for purchase. My credit card gives me 1.5% back in rewards for every purchase, for example. I also have the ability dispute charges I don't agree with.
Bitcoin may be cheaper for merchants to use when it comes to low volume merchants. High volume merchants make special deals with the major credit providers.
For in-person transactions, cash has zero fees and is immediately transferable. Checks have zero fees but take time. EFT is used for recurring billing quite a bit by merchants and it normally has zero fees.
Credit cards have fees but they are not comparable to bitcoin because you are not using money you have. You are borrowing money you don't have and spending it when you use a credit card. This allows people to make purchases they can't afford and that gives vendors the ability to sell products and services to people they wouldn't have buyers for otherwise.
Because bitcoin doesn't have a readily apparent advantage over any other method of purchase, international transfer is normally touted as bitcoins advantage. However, there are many ways to do an international transfer with currencies that do not incur things such as wire transfer fees.
This list compares ways of sending money abroad:
http://www.consumerreports.org/cro/2012/03/the-best-ways-to-send-money-abroad/index.htmIt is missing newer services like Transferwise which also may be cheaper. There is no inherent advantage bitcoin has to international transfer over other methods of transferring value.
Because of all that, the future value of bitcoin is entirely speculative in nature. Whether it will be worth more or less in the future is entirely dependent on individual perceptions of value.
A bitcoin is only worth what someone is willing to pay for it. No more and no less.
If you look at "how many bitcoins will exist in the future" or any other method to try and infer what the price will be in the future, you are looking at things incorrectly.