If Bitcoin to be international currency in the future?

As an actual day to day currency.. I disagree.. it certainly can be used anywhere and be sent to anyone as a simple store of value.. but the logistics involved with it being a currency in my opinion is where it becomes nearly impossible.  Currency relies on prices of things to be less volatile.. for example you can't buy a cup of coffee with bitcoin and the price drop 30% the next week.. that would be crazy for a business owner.  2nd, the fees and transactions per second are just simply too slow for mass scalability... to speed up the transaction speeds of bitcoin and make it cheaper, you would be risking more centralization and some of the things that make it so great.  I think bitcoin is a wonderful store of value and remarkable as a technology, but as an everyday use currency,  I just don't see it.