everything requires a process, of course we can't replace it completely or totally, maybe to be able to do that we at least have to go through 2 generations so that all can access crypto in the internet world. at least being an alternative means of payment is already a good achievement now
I don't know what you mean by not replace it totally. In my understanding replace means to remove something as a whole not partially. 
People already use Bitcoin as an alternative payment tool, but still allowed in some countries. Yes, it needs the process to spread Bitcoin as the payment alternative around the world. Maybe it will take more than 5 years again to see Bitcoin be used as a payment tool alternative in most countries in the world.
Those using it for payments frequently is a very small minority. Hardly anyone would use Bitcoin as there is nothing that you can pay with Bitcoin for to still justify the extraordinarily high transaction costs. Only if you buy a house or a car it would make sense to use Bitcoin maybe. Apart from that it is a pain in the ass still to do shopping with Bitcoin specifically, other cryptocurrencies might work out better but there are hardly any cryptos that are widely accepted as a means of payment.