The US dollar is not on the cusp of death[1], but it is becoming somewhat devalued compared to other currencies, and I think it will continue to for some time[2].
What I’d suggest is the same thing I’d suggest anyone, especially anyone who’s just starting out, the Boggleheads Three-fund portfolio. If you’re especially concerned about the US dollar, you could (1) put more weight on your international stock index and/or (2) add an international bond index to the mix, like this one.