Several years ago, most of one country's large banks failed and were taken over by a government agency.
Conclusion
The agency is unlikely to achieve its goal (i.e. the banking system will not be strengthened).
Evidence
If the former owners of these banks buy them back, the banking system will not be strengthened.
If an argument gives us a conditional premise X → Y and then concludes So, Y. then what is the missing idea?
We're missing this: X.
We know if the former owners buy back, the banking system will not be strengthened.
Our author concludes the banking system will not be strengthened.
Goal
So, we want to hear that the former owners will buy these banks back.