To this day, my very favorite D&D campaign happened in a Homebrewed world that was heavily M:TG inspired. Note that it happened a few months after the Legends set release, and therefore before 3rd edition. It was a heavily home-ruled AD&D 2nd edition game.
The 5 Gods who existed in the setting were the 5 Legendary Dragons in the Legends set (I really forgot their names). There were 4 'countries', each ruled by a god, and the fifth God was an Overgod, and somewhat Neutral. Other than that, the M:TG influence came in the way of homemade monsters based on M:TG monsters (hypnotic specters really stand out there) and artefacts (Our Campaign goal was to get the Chaos Orb, for reasons I forgot).
Anyway, the point is, the campaign setting was awesome, and that was in part due to the M:TG influence. At that time, I (and the other players and DM) were heavily into M:TG, and the references to the game were awesome. Some of it were also due to the DM (who was awesome) who managed to modify AD&D enough to make it really, really good.
But anyway, his setting as written would never have been published. It was inspired by M:TG, no doubt about it, but not enough for the company that owned M:TG to be happy about it. Planeswalkers didn't exist, many things were modified, etc.