This is the chart of Bitcoin's Avg. Transaction fee:
https://bitinfocharts.com/comparison/bitcoin-transactionfees.htmlRight now the median fee is about $2. After lots of halvings the reward won't be enough to satisfy the miners. I guess that after a decade, bitcoin will be more widespread, as a result, more transactions will occur every second. Won't this increase the median fee? If it does, bitcoin will start being a not-so medium of exchange. Imagine paying $5 for a transaction. Even paypal doesn't charge that much.
Increase in fees happens when there is a long line of transactions to be confirmed, and there are always people who are ready to pay higher fees to get miners to confirm their transactions first, and as more people are ready to pay even higher fees, the more that this will keep on increasing. But I believe that there is going to be a solution to this in future. Its best that we just keep cool and keep following with whatever events that are taking place for now.
This is the reason why SegWit was introduced, to help make things faster and easier, as the Bitcoin Blockchain will be able to contain more transactions in a block. This wouldnt work though, if its not adopted. But I believe that the devs are steady looking into this. For now you can make use of wallets that allows to choose the level of fees you want to pay for a transaction.