What's an extremely high fee? What's high for you may be low for someone else.
In 2019 the average fee was around $1
In 2021 it was $2. In 2023 it went up a bit again, but stayed around $2.5.
I don't count extremes where due to congestion it skyrocketed above $20, which happened in 2018, 2021 and 2024.
What makes you think the fee will be much higher in the coming years? The history points towards a slow and gradual increase. You can still send a $2 tx if you want and it will go through.
Bitcoin transaction fee is paid in bitcoin or its smallest unit, satoshi.
Assuming that in future, Bitcoin continues its adoption and price growth, with higher price of Bitcoin, transaction fee will become higher with same fee rate. Not yet considering that with bigger adoption, same capacity of Bitcoin block to handle number of transactions, people might have to join fee rate race and use higher fee rate, this will be a second factor to cause higher and more expensive transaction fee.
Transaction fees depend on demand that is usually higher in bull market but if people know well about Bitcoin mempools, they can wait and plan for transactions in times of mempools without congestion.