An engineer holds a license such that they can profess, which license is conditional to the respect of their code of ethics (and a bunch of rules). If they do not follow those conditions, their license can be revoked.
So what if they lose their license? They can still write code and do harm.
Yes, indeed. As it stands right now, the reality of the engineer's license is such that it doesn't fit very well the software world. The vast majority of companies couldn't give less of a damn whether you are licensed or not. However, it depends.
Regulations might eventually come in place to force software producers to hire only licensed engineers if the nature of their business is prone to put the public in danger. And as technology grows ever deeper into our lives, the danger that consumer apps can cause on the public is ever growing as well. For instance, breaching a user's privacy can be enough info to grant an ill-intended operator access to the user's e-mail through social engineering, from which it is then often trivial to gain access to that user's bank informations. You don't need that much imagination to figure out a scenario where a user's life can be turned to shit by some software abuse.
Given that this risk is ever growing, the possibility of a code of ethic on software business is plausible. Say in X months, the government of country Y decides that companies hoping to run a social network available on their territories must hire licensed software-engineers, and have them all sign-off any code that is presented to the public. That software engineer they'd hire would have to put their license and career in jeopardy if they were to implement some evil feature.
Before Québec's bridge, engineers didn't need a license to build infrastructure. The parallel between the current situation and the past isn't too hard to make.