I traveled over the new bridge over the St. Croix river on Saturday. It's an impressive structure and it will make life easier for people in western Wisconsin to get to Minnesota, but unless current conditions change, it may not have a huge impact on travel in the region. On either side of the bridge, the infrastructure to match it does not currently exist.
The amount of development on the south edge of Stillwater, on the approach to the bridge, means you need to go through multiple stoplights, which will back traffic up substantially. On the Wisconsin side, drivers encounter a series of roundabouts that impede traffic even further. If you want to head south from the new bridge to get to Hudson, prepare to go through three roundabouts and then slog down an underdeveloped 2-lane highway into town.
The I-94 bridge over the St. Croix is 10 lanes wide and is built for a lot of traffic. The effect of the new bridge on the I-94 crossing may be less than people imagine.