Yeah, he has, but, every rapper gets a 5-7 year run. After that you will either fall off or be a factor in the game. If Drakes new album sounds like his mixtape, it will be the beginning of the end.
What Kendrick did with this album is solidified his place in rap because he changed his sound, and its banging. Plus its different sounding then other stuff that's popular now. His album is consistently selling, and is already gold. When he drops "these walls", its a wrap because females are gonna love that shyt.
Kendrick does music the old way, he takes his time with releasing music, and doesn't oversaturate himself. That is how you do it. You want people to fiend for your music, then when you release an album, spread out the singles. It will sell slowly, but it keeps your career lasting longer or more impactful. That is how albums used to sell. People think artists used to always go gold or!platinum in the first few weeks. No, that only happened with rap, for the most part, and it was game to these labels. Most artist sold records slowly, but ,consistently. Eventually going gold or platinum.
Kendrick is doing fine. If he did the album on a medium budget, he can recoup, and still do more music because labels just want to make a profit. If he had a big budget, it might be over or he will get one more chance but his next album will sound like the rest to recoup some money.