> Who will use bitcoin without it having a stable value?

It just need to be stable enough for the length of the transaction. As long as you keep the bitcoins moving, the gain/loss will distribute itself over everyone and it won't be different than any bank fees.

Let say I want to buy something from you for 20$ USD, I'm in Canada, so I buy 27$ CAD of Bitcoin on a local exchange (so I buy it from someone that essentially just sold something), I transfer the resulting Bitcoin to you, you then sold it as soon as you can. Even if the Bitcoin price is losing 25% today, if you can do all that in 2 hours, you will only lose about 3%, which is similar to Visa fees. Ideally you wouldn't hold them for more than 5 minutes and it would all be automated behind the scene without your knowledge, probably through your bank if they move quick enough, but that could be through a third party too (which is the beauty of it all, you depends on no one).

That's an ideal world though and I feel like that's an utopia but that's how I see we can ignore the stability issue.

The fees are a much bigger problem. Bitcoin is unusable, it s a speculative vehicle for rich people. Zero-fee , or very-low-fee cryptos (i remember stellar, iota, raiblocks, even xrp) would be very usable if they had a large userbase and a very easy way to buy them. One of those has to focus on real world growth, i.e. get many websites to support them by providing a dead-simple payment solution.

I think there are ways to make them less volatile. For one, don't list them in any crypto-to-crypto exchanges, instead allow only dollar cash-ins/outs, or limit the amount that can be exchanged to some fixed value like $100 / hour. Speculation and greed is limiting the prospects of most coins.