I think the influx of more rappers is a double edge sword.
It's definitely given us more weak rappers.
On the other hand it has opened the genre into many different styles.
I think biggest change is in how we listen to music. Majority of people don't listen to "albums" anymore. They listen to singles, and artist on a song by song basis, because are attention span is so short. I think this is the major adjustment to come in the next 5 years, I bet we will have artist that don't even release albums, just singles through Itunes.