I don't know about that June date because they wrap up production on Madden in June. By then, the most changes that can be made are minor if any can be made at all.
If they're going to do this, they should consider releasing beta's sometime shortly after the Super Bowl. By that time there will only be about 4 months of production time left and they'll have more than enough to show for the communities to test. The beta's should allow for offense, defense and special teams, but be more like a demo in terms of options and only 2 selectable teams. You don't wanna give too much away even for testing purposes.
There should also be a limited franchise only beta.
The more chances the communities get to lend direct input the better.
Someone mentioned that games like Halo and other big time titles have more production time which makes this easier. That's a good point, however from watching some of the things people have brought to the Madden Team's attention and then seeing them fix it based on that feedback, it tells me that some (not all) issues can be fixed in a reasonable amount of time if they're caught with enough time left, but sometimes it just takes "outside eyes" to catch them.