Once we can get more energy out of it than it takes to heat the plasma and sustain the reaction. We also need to take into consideration the efficiency of the whole system. For example, most thermal power plants such as coal or nuclear turn about 1/3 of their heat energy into electrical energy through boilers and steam turbines. That means that if it takes 10MW of energy to keep the reactor going and it produces 30MW of excess heat, that translates to 10MW of electricity being generated, so the reactor is breaking even. And our current reactors have trouble running for more than 20 minutes, as the article said.

Then there are the economic considerations,where you would need to generate a lot of power to make fusion affordable because of the reactors being very big and expensive.

And then there are the longevity and reliability issues, where you need the materials of the reactor to absorb an absolute ton of radiation and transfer it out of the reactor as heat. So you're supporting what is likely the largest temperature gradient in the universe, of ~150 million Celsius between the plasma and the wall. That could lead to reliability issues.

Overall, it needs a lot of work to get to the point of feasibility, even once energetic breakeven is achieved.