I hate to be "that guy", but how does one define a musical genre as "dead"? if it's a definition of popularity then we could ask the same of all popular music genres of the past 70 years (because lets not forget that "popular music" is still very young in terms of the arts as a whole) at one time or another; is psychedelia dead, is funk dead, is reggae dead, is blues dead or have the genres simply evolved into something else more popular leaving the original less popular? all of these genres have sparked so many new genres that even the question of popularity is a difficult one, especially when used in such broad terms. is rap dead is like asking if cars are dead; people still buy cars but the model T ford is not as popular as it once was. if you asked "are 90’s ford’s dead?" then you can at least quantify it. As with music, people may not have the same tastes as they did but newer manifestations of the genres have replaced the old. Rap, like rock, is now split into so many sub genres that all have their own markets and fans. for example, i love late 90's grunge, but i'm not a fan of "death core" or "rap metal", but in broad stokes i can still be classed as liking rock music. assuming we mean "dead" as to be not as popular as it was at it's peak; if asking the same question "is rock dead" then i'd have to say no. if asked "is new metal dead" then i'd say "probably"
This evolution of music, and all arts, is part of the nature of the arts. Music, more than some, is victim to trends and fads due to its link with different youth culture movements, and often it is the choice of music that defines these movements. “hippies”, “Yuppies”, “mods”, “rockers”, “grebs”, “rude boys”, “chavs”, “moshers” are all distinguishable by their choice of clothing, life style, and musical taste. Now, last time I checked, the number of “mods” in my local area is much lower than 50 years ago, but is that because the music associated with it has “died” or because society has changed, or both, or neither?
In terms of “Rap” all sounding the same, this all comes down to the ear of the beholder. To me, all paintings in a similar style all look identical but to judge them as the same misses the point. All art has at its roots a desire to express what is within the artist. For this expression to reach as many people as possible people do one of two things; either they go out of their way to create something completely new and bold that has no proven track record of reaching peoples attention, or they embellish on what is already, or has been, popular, using it as a backbone to their work to build upon. Evolution isn’t the sudden jump from one thing to another with no obvious link, it’s a progression from one thing to another, taking the best bits of something and adapting to fit the needs of the new. Can you hear the similarities between the Beatles and Kanye West? Maybe not, but they’re there!
I personally am not a fan of “rap” or it’s many, many sub genres, but I’d never belittle it because it’s their form of self expression, and there are people who can and do relate to this. However, the “quality” of this self expression varies wildly, and is much like public speaking. Some people can stand in front of 100,000 people and share their views in a well presented way that people can easily relate to, whilst others just stumble over their words trying to put a point across but ultimately failing. The internet and lack of “quality control” on things like youtube and other social media has meant that there is a lot of music available to the whole world at the click of the button that is like the speaker stumbling over their words; they have a point to make but haven’t acquired the skills to make it in such a way that people will fully listen. Sometimes they have a very good point to make, and do it very well, but the point has been made before, in which case people very quickly tune out.
I fear I am starting to rant so I should probably conclude; “rap” music isn’t dead. Some genres of it are certainly less popular than they were but the genre as a whole is now so entrenched in main stream culture that it’ll probably never die, but it will continue to grow and adapt as society grows and adapts. A better question may have been “is rap music as popular as it once was as a whole” in which case the answer may be very different.