Limitation of amount for a coin like bitcoin or any other altcoin as well low inflation makes it only worth to use as wealth storage.
Gold were also a payment unit till middle of last century, but now it is only wealth storage and speculation object on market.
Same is almost happen with BTCbitcoinBTC, moreover it is to volatile to be used as payment.
I don't think this is true. Low inflation or deflation are just theories people put forward for bitcoin. It is important that it always shows up on Bitcoin's price. If we say Halving, cutting the supply rate makes an asset that will increase its value is not correct. it also depends on human needs. I believe that bitcoin will never be put on our market, because every transaction is anonymous and therefore money laundering will be even easier. the government won't let this happen.
Bitcoin transactions are not anonymous, just it is a bit harder to identify, but with enough computing power all transactions could be followed backed.