How does any of this make sense to you? GMO's don't have anything to do with crop diversity, in Argentina there are hundreds of different kinds of GMO Soy already,
Crop diversity is killed whenever a new "better" crop is found (from purely an economic standpoint). GMOs by definition are made to be better crops than the old ones, and as such they tend to supersede all that came before.
Only that this is counterproductive in the long term because losing diversity is bad for various reason (for example farmers not being able to produce niche-products because they're not economically advantageous anymore, or losing the possibility to eat delicious food).
This has little to do with GMOs being GMOs, it's just a consequence of extremely centralized power in industries and they're a way for corporation to basically kill all of the smaller industries and get monopolies (funny how the promote the "save world hunger" ideas of GMOs when basically those industries are a big part of why there's world hunger in the first place). You can see this in traditionally agriculturally diverse and rich areas like Tuscany. For now a lot of farmers survive because here people tend to actually value a lot all the difference varieties and local specialities of foods, but the economic crisis is doing a good job at killing all little local industries in favor of super mass produced goods at the lowest possible cost.
Coincidentally, this is also why i'm all for GMOs in terms of energy producing plants (algae mostly) or cattle feeding. Because there all of my concerns are not an issue (diversity not existent already, cattle feeding being basically always made of discards).