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.
Yes and this is inevtiable.
Be reminded that the transaction fees are what miners get as a reward from every transaction they process. As the supply of bitcoin eventually gets mined up, the price will significantly increase along with the transaction fees but the price may also differ depending on the supply. Just think that when all of the bitcoins are mined, what will be the main source of income of miners? They will now depend on these transaction fees and that will be their main focus.