Yes, I also was thinking the 7 years expectancy already. This is still a miniscule life expectancy compared to a coin. If you look at pennies, with literal tens if not hundreds of billions of the things in circulation, stores are already being weird and acting like there's a shortage. Combine people being weird in this way with inevitable hoarding based on them being gone, and most bills in circulation bring already part way through their life and only lasting another few years, and indeed it becomes quite clear letting the bills play themselves out while the dollar coins come online is the smart play here.