I don't think they're expecting to even break even off this particular unit.
It's basically a full scale prototype for the capture tech to see if the tech actually works at a reasonable operating cost. If it does, they'll roll it out to the other coal plants, at lower cost now that they know what they're doing with it.
If it doesn't pan out, they're going to have to find something else to provide power, as the coal plants will have to be shut down when they hit the 50 year mark, as there's no way for them to fit under the CO2 emissions regulations* without the capture tech. And that 50 year mark isn't all that far away.
In the latter case, unit 4 at Boundary Dam will shut down in 2020, followed by unit 5 in 2023, unit 6 in 2028, then Poplar River's units in 2031 and 2033. That's nearly 1/3rd of their generation capacity and most of their base load.
*Existing power plants are grandfathered in. The CO2 regs don't apply to them until 50 years after their commissioning date.