It will change the ratio garanteed.
For how long is another story.
For example, equal build may give slightly more atk and def but not as much as a atk building. Prehaps the mean average between the 2 currently? To help balance this, plunder from this building may be slightly lesser. For defence buildings again run mean atk bonus between it and the current average troop building and take that added number and add to def end as well. Reduced plunder again maybe.
This will make the builds more appealing but with less attack and plunder than forges but whatever ammount that will make forges still run as built.
The main difficulty is someone saying 'this type of building is the best' and everyone run that type, even if it is balanced ... as far as the Starcraft reference goes, this could be complaints that roaches are overpowered and everyone runs roaches or Protoss mothership rush etc which all are risky counterable build orders..
Also, expect changes among the non LCed first I expect as people will be relunctant to tear down 8subs +