Local Business community is irate that they chose July instead of August for this. The airport itself has been undergoing a complete renovation, (and it is an amazing and massive improvement) but the July closure is likely going to be a huge hit to the local economy.
We have a vacation home up there and it hasn't affected our bookings for July, but I'm not sure people generally book their flights that far out. Still, I imagine Missoula will pick up the slack. There's a percentage of people who fly there instead of FCA anyway, as it is generally cheaper.
Hopefully once the airport renovation and expansion is complete, Delta can resume the ATL-FCA flights they had pre-Covid. One can dream, anyway!