The Answer to that is; no, it won't
Bitcoin has invoked an almost religious Fervor among its Supporters - but why won't it replace Fiat Currency?
It's Infrastructure is chronically unreliable....
Have you ever tried buying any?
There are many Companies where you can do this - except every one I've used, tried or signed up to is hopeless and unreliable.
There's one - where you can use your Visa Debit Card - which keeps getting declined when you do. Another, where you have to do it via Wire Transfer - which can take up to 8 Days and cost anything up to £25 in IBAN Fees, or you use one of these Merchants - who are hopelessly unreliable - and you spend days grappling with the Website, Errors, and the like - and Email Inquires that can also take days. Some, where you have to buy Euros before you even deposit, others that take anything up to an Hour before your Deposit reaches your Wallet Account, and Exchanges where you have to hope the other Guy is honest. Some charge exorbitant Fees - and then there's the Disparity between what you buy them for and sell them - anything up to a £200 or 25% Deficit. You lose almost that much on something you bought in a Shop as soon as you leave the Premises.
Then there are the myriad Scams involved - while all of it is a shambles run by People who don't seem to have any common sense.
Yeah, we all know that the current Financial System is flawed - and about the Bailouts a few years ago, the other things that go on in the Recesses of it all, the Subterfuge, but until someone creates an Alternative that doesn't give you Stomach Ulcers trying to use - or cause days of Stress and Aggravation - then Cryptocurrency will always be regarded as a sort of Monopoly Money that you can't even buy a plastic House with. We also know that Currency now isn't backed by any Gold or Silver Standard - and is just a Number whose Value could, and sometimes has plummeted.
I suggest a Vendor that does accept Visa Debit, and one that works, that is as quick as any Bureau de Change might be when you buy them, and where you can sell them either for the same Amount - or whatever the Exchange Rate might be. Who could email Coin to you rather than you having to wait an Hour before they arrive, and one that is discreet.
I have just been through a Process that took over a Week to have Documents verified, where Bitcoin went up by about £250 when that went on, only to find that a Dysfunction now exists with the Merchant you deposit with - via whom you buy your Coin from a Wallet Provider. Ironic considering they issue a Visa Debit Card - but you can't deposit with one. If it was set up properly it is instant, reliable and - above all - refundable in the Event of a Dispute.
Also, and this is the most crucial part, Bitcoin will stop being produced in about 2040, which limits the amount available to anyone, so while Fiat Currency can almost seem like it's being printed like there was no tomorrow - at least it's available.
So, until you can do everything from Busk for Bitcoin to buy and make a Transaction with it that doesn't mean the World goes into Metastasis while it grinds into action it will never become the mainstream Currency.