Oh, don't get me wrong. I'm happy Lesnar is out of the picture right now. When all of your matches are utterly predictable because you literally use only 1 or 2 moves (your signature and finisher), and your opponent has to dumb down to using only his signature and/or finisher, then it is high time to hang it up and call it a day. Same with Goldberg. Both are past their primes and should just stay away.
However, you know Vince. And Lesnar is too big of a name for Vince to just "let go." At some point, I expect Lesnar to return. Whether or not he challenges Drew to reclaim his title, or realigns himself with Heyman to go after Reigns, I'm not sure.
It would actually be somewhat refreshing if Lesnar returned as a face to take on heel Reigns + Heyman. Or heel Reigns gets too cocky and arrogant and "fires" Heyman. Which causes Heyman to bring back Lesnar to get revenge on Reigns.
Frankly, I don't see how Lesnar can operate independently without Heyman. So, if/when Lesnar does come back, I expect him to be involved with Heyman in some way.
At this point, you've exhausted all of Lesnar's biggest potential matchups and feuds. What's left for him there to do?
Lesnar vs. Triple H - done multiple times
Lesner vs. Undertaker - done many many times
Lesnar vs. AJ Styles - done
Lesnar vs. Daniel Bryan - done
Lesnar vs. Seth Rollins - done multiple times
Lesnar vs. John Cena - done multiple times
Lesnar vs. Roman Reigns - done to death
Lesnar vs. CM Punk - done
Lesnar vs. Goldberg - *vomits*
Lesnar vs. Drew McIntyre - done
Lesnar vs. Randy Orton - done
Lesnar vs. Samoa Joe - done
Lesnar vs. Finn Balor - done
I think the one guy left he hasn't really feuded with is Fiend/Bray Wyatt, and I wouldn't expect much out of that. The bloom is off the rose for Shinsuke Nakamura. Unless he gets some major league repairs done, he's not sniffing the main event again.