One crazy thing about the Internet is that false rumors get spread on a regular basis. One often heard rumor is that 50 Cent & Eminem are no longer on cordial terms (but not necessarily on bad terms). The reality of the situation is that the two men have both been very successful in their careers and run major business operations that attract each of their attention more than the Rap Game.
The Rap Game, however, is still the number one way for any veteran to keep their name buzzin. One should never be surprised to see a rap "legend" team up with a new generation artist if it'll help bring attention to their name (i.e., their brand). Two other recent examples include Wu-Tang Clan when they were featured on Logic's album and Styles P's collaboration work with Dave East.
Catch Ed Sheeran's latest track, Remember The Name, featuring Eminem & 50 Cent, below.