"terminal supply" is a mathematical abstraction which doesn't have any bearing on the real world. The supply of Monero is never infinite. at any point in time it is algorithmically determined.

In about 17 years it will be on 21coins. Inflation yes, but not really a concern I would say, in a practical way.

Just remeber how compounding works. 2% means you double the supply every 36 years (technically cloaset to 35) All else being equal you've essentially lost 50% of your purchasing power in your working lifetime