Bitcoin should become more stable in order to be a popular method of payment. Technically, crypto-currencies are not money, but information blocks. Their value isn`t tied to any economy of the world, and the trade and support of digital cash is carried out constantly and doesn`t depend on standard world trading sessions. Such independence has advantages, but this also frightens, since the price of bitcoin remains unpredictable.

Bitcoin should become more stable in order to be a popular method of payment.Bitcoin or Altcoins have the potential to compete with fiat currency. they can be treated as a method of payment and a safe storage of value. 

We are talking about decentralized money and still we want to regulate it ? It is like we are standing under open sky on a shiny day and want to dry up our sweat ! Bitcoin is getting popularity and  it is safest if you know how to deal with it. And if you talk about potential, Both fiat and crypto have potentials. They will not replace each other. rather they will be side by side.

The more you will educate your community about crypto, the better. And Crypto will become popular globally

In specifications, yes, bitcoin fulfills all three of these. However, due to the fact that there aren't enough places to spend bitcoins and use them as currency, it cannot display how good and effective it will be as such. Due to this, people outside the ecosystem think that bitcoin isn't an effective means of payment because there aren't sufficient data existing about the reliability of the coin. Most retailers and services who removed bitcoin on their method of payment feel that it's tanking because it's not wante, but that's not the case in actuality.

Many factors.
We need a stabler price for bitcoin. It fluctuates too much that I dont think anyone dont check the price to see if he or she should sell bitcoin before even send a bitcoin payment.
We need the goverments to accept bitcoin being used.
We need banks to accept their customers to deposit and send money to buy bitcoin.

I think that the main problems used to be popularity, availability, transaction cost and transaction price. Transaction price has been mostly fixed by segwit, transaction time will be fixed by the lightning network, I believe we are doing good as far as popularity is concerned, but the availability is still slacking. IN many countries you just can't easily buy your coins due to various bans and restrictions, Internet and power shortages, lack of safe exchanges. It will take more time, but it should happen eventually.

Bitcoin being a currency depends on how many people actually get to buy and sell with the bitcoin in their possession. People in the bitcoin market have to accept bitcoin as a form of payment for their services. We don't have to look at governments to give permissions for bitcoin to be legal tender. It is the money of the internet; no one can stop bitcoin from being used as a currency.

Store of Value : YES
Medium of exchange : YES
Unit of Account : YES
Bitcoin has much more than above features like anonymity, personal privacy, financial freedom etc to make it perfect payment method.

Bitcoins has fulfilled all the properties you mentioned to make it a popular payment method, the only obstacle is government full acceptance of it  as a mainstream currency.