I really want to reiterate that I think an area of law topic will work a lot better than a list of cases topic. Especially for the landmark cases proposal, I believe there is going to be a shocking paucity of literature advocating the overrule of a landmark decision. For sure, Brown v. Board isn't working, but the solutions normally don't involve an explicit overrule of Brown, but rather a modification of the policies that have derived from the deicision, or a call for stricter enforcement of the principles embodied therein. Of course, many conservatives advocate overruling Roe v. Wade, but I think most of the really smart literature assumes that will never happen and approaches the abortion debate from a perspective of limiting the effect of Roe rather than advocating its reversal.

With an area of the law topic, you will find better, well-supported Affirmatives. More importantly, there will be more opportunity for the Affirmative to create strategically sound Affs. With an overturn a list of decisions resolution, the Negative will have the upper hand with a huge variety of PICs. Given all the discussion about Negative bias of late, I don't see why the community would want to limit the Affirmative to overruling a list of key cases when there is very little literature to support that approach and very much literature to support a plethora of Negative PICs.
 

I'm just not sure that if the resolution requiring the Aff to "overrule" Morrison that your proposed plan would be topical.

Just because the USSC declares that Congress has the authority to enact "civil remedy provisions for victims of gender based violence" doesn't necessarily mean that it has overruled Morrison, though for all intents and purposes it has. The Supreme Court could theoretically just limit Morrison to its facts, and rule that another similar statute providing a similar remedy is constitutional. It seems to me that if you want to put "overrule" in the resolution, Affs will be required to defend the actual overruling of a decision. Of course, I've been out for a while so I'm not sure if T debates have changed....