I think there is some merit in your overall concept, growing them as a hedge in containers. But, I kind of question some of the details...

... for example, "one foot concrete containers" ... why concrete? Isn't it heavy and somewhat prone to cracking and shattering in the winter? While regular (construction grade?) concrete blocks and patio stones seem to weather OK overall, we had a lot of problems back when I worked at a garden center with decorative concrete shattering in the winter, and customers would be unhappy... so, you might want to consider that depending upon what you're considering using for a planter. And, there is the weight issue -- do you mind lugging these around?

The other main issue I see with this is just the small size, seems like you're asking for trouble because it would dry out so quickly.

Would the bushes root through into the ground? Quite possibly, many woody plants will do this. I have to move my containerized plants at least a couple times a season if on soil or over mulch to avoid rooting in.

I would offer the alternative suggestion that you plant in some kind of large, say minimum 20" diameter if not larger, containers that you just let sit above-ground. Nanking Cherry is hardy to Zone 2, basically arctic or sub-arctic conditions, so you shouldn't have any trouble overwintering in large containers even in Wisconsin.

I should clarify the containers. I have leftover 16" long x 4" wide x 8" tall concrete construction blocks from my raised beds project, and 4 of them together make a nice tiny raised bed/bottomless container. They won't crack in the winter, since they don't have a bottom. They will not be moved, since they're horribly heavy. I just can't plant in the ground since there are buried power lines.

Aren't the cables 2 feet down? I thought there were rules about the depth of buried cables. Maybe it is only 1 foot - anyway - I would cut a square hole in the landscape fabric to help them root in and half bury the cement blocks to help them stand up. It will be beautiful in the spring when they are in full bloom.