Well, in my opinion, I think if that will happen then maybe a single satoshi is worth more than your dream car or a house. It may sounds funny but could still be possible. To early to speculate but yeah still has to take a long, long journey and I don't think if humans still exist during that time. Actually time can really tell us that and for sure no humans could pinpoint what would exactly to happen that time only speculations are more acceptable. As what I have observed transaction fees are some kind of an issue here too as all coins are mined and will fully flow in circulation with  demands too high that makes the price to make the value of a single satoshi into like thousands or even hundreds of thousands of dollars.