1. Most people don't want to gamble their everyday checking account funds on something as volatile as BitCoin. It's success could well become the reason for it's demise (which futures might play a role in).
2. The scarcity factor. While that has certainly played a role in it's rise, a currency for general circulation needs more liquidity.
Bitcoin seems to have no need of being a currency, at least for the time being. It has become more of a commodity and a store of value in the eyes of general public and new adopters. The futures trading will also strengthen this position. It doesn't make much difference now whether it finds widespread acceptance for buying/ selling or not.
I would keep your eyes open for a crypto that brings the following factors together.
1, Greater quantity/Liquidity: If your going to use it to buy groceries, gas, bridge tolls, etc., you need easy access to adequate quantities.
2. More price stability:
Do you really want a currency whose value can fall by half between the time you deposit a paycheck and the time you pay your rent? We've seen that with fiat currencies. It's called hyperinflation.
Cryptos have been coming and going for quite sometime now. None have approached the widespread acceptance as well as authenticity of BTC. You need the distributed infrastructure running on insane miners around the world to make a strong blockchain and a strong currency. This doesn't seem to be happening for other coins so easily. Its a mad rush to the BTC front gates. Few people have the time or inclination to loo out for other crytpos vying to replace BTC.
Though if such a situation arises, it'll be pretty painful and may make everything go bust for a while
3. Some investment quality (inflation insurance):
Imagine a crypto whose price was pegged to something in the real world. It could be gold or silver (or any other commodity), but it could also be pegged to the dollar adjusted for inflation, so if inflation is 6% your money gains 6% against the dollar as you hold it. With a peg like that you would have an incentive to get out of dollars and into the crypto as fast as possible, but without a scarcity factor it would not drive the price up or become hard to get. This structure would give average people the ability to hold their ground against inflation. If the dollar ever collapses, your protected.
4. Broad commercial and acceptance with banking support:
Imagine a crypto debit Visa card that allowed you to hold a crypto currency, but pay in your choice of dollars or crypto. So you buy some thing on amazon and they take payment in crypto, so you select crypto, but then you buy a loaf of bread and they don't take crypto so you slide your card and they get paid in dollars (your bank converts your crytpo into dollars at the time of sale and pays the store in dollars.
Both these things you are proposing are good qualities for a currency of course, but it doesn't look like that bitcoin depends on this recognition anymore. Even if so, Bitcoin value does increase over time and it is widely accepted, atleast the most commonly accepted currency now. So it already has these two qualities.
What we also need to keep in mind that the bitcoin team has the oldest devs in this line. Every innovation worth mentioning has started off from them. Its hard to find another crypto whose innards both technically as well as socio-economically have been debated and propagated so much. That makes it robust.
The development is agile and Bitcoin seems to have taken everything in its stride. Once we can get over the debate of LN leading to centralization, I think we'll be well on our way to see BTC as the Prime.
As far as similar growth is concerned, I think 2018 will begin with cyclical adjustments that happen with plenty of new investors onboarding. This will be the time for Alts to grow as well as those ICO roadmaps to show that they are worth anything or not.
Once we get some major news from successful ICOs, regulations for ICOs will most probably kick-in to sanitize the space. Thats when we'll see another big jump in BTC.
If there's a currency that can potentially be replaced amidst all this, its ETH. BTC will hold its own in my opinion.
