Yes, doing something is necessary.
CC BY-SA is a copyleft license. If you incorporate something that is CC BY-SA into a larger work, that larger work must also be released under a CC BY-SA or compatible license.
Creative Commons does not recommend the use of a Creative Commons license for software. Their licenses do not recognize distinctions between source distribution and binary distribution, do not discuss linking, and do not discuss patent grants. Note that the CC0 Public Domain dedication is acceptable for software.
Right now, if you took copyrightable code from Stack Overflow (or any Stack Exchange site) and used it in your application, your application would need to be released under a compatible license. This is not desirable for an organization that wishes to release closed-source software.
If Stack Exchange migrated from CC BY-SA 3.0 to CC BY-SA 4.0, it would make it slightly easier. The Free Art License (analysis, comparison) and GPLv3 (analysis, comparison) are compatible with CC BY-SA 4.0. This means that if you have content licensed CC BY-SA 4.0, you can use it in a Free Art Licensed or GPLv3 licensed project. You can also very easily include Free Art Licensed software in a post on Stack Exchange. However, you cannot as easily include GPLv3 licensed software as it is only one-way compatible with the BY-SA 4.0.
Even after a migration, there are still issues that would need to be ironed out. Most open source software is released under a permissive license - 25% MIT, 22% Apache 2.0, 6% BSD 3-Clause. There are also a large number of closed-source software projects that exist. Due to the viral nature of the ShareAlike clause of the Creative Commons licenses, the Free Art License, and the GPL, these closed or permissively licensed projects would not be able to use any copyrightable code posted on Stack Exchange sites. That's closing the door on a lot of people.