Even if it was pegged to real inflation, it would still be trustless as well as project my purchasing power better into the future than fiat. Therefore, I would still use it.

So, to up the stakes a bit, let's roll with another scenario: A fiat currency has emerged that does not print whenever they can, in fact, they reduce supply whenever feasible. In that case, it could hold purchasing power even better than bitcoin.

At that point, I'd have to ask myself how much am I willing to sacrifice in future purchasing power to hold on to bitcoin? Or in other terms: How much do I personally value a trustless currency over one that requires trust, but has managed to offer better preservation of purchasing power (but could just as easily change in future)?