Future Plans For Brock Lesnar

The working plan right now is after Brock Lesnar defeats Goldberg at WrestleMania 33 for the Universal Title, he then will be defeated by Roman Reigns sometime over the next few months, possibly at SummerSlam.
According to Dave Meltzer on Wrestling Observer Radio, Brock Lesnar is likely to remain affiliated with WWE in some way after his contract expires next year.
The whole idea for Lesnar over the years has been to push him as an unbeatable monster who runs through everyone only to ultimately lose to Roman Reigns and as we have noted before, this appears ready to happen next year at WrestleMania.

Meltzer went on to say that he can’t see Brock leaving given the limited schedule and the money he gets so it will come down to whether Vince McMahon feels paying Lesnar that much money if it is worth it. If there is another viable company/competition who will look to sign Lesnar, Meltzer feels the chances of Vince ponying up the cash for Brock will increase and in all likelihood, he will remain with WWE.
The tentative plan is that Brock Lesnar will do more shows from this point on as this is the final year of his three-year contract, especially now that his UFC plans are pretty much over.
While he will never work a full-time schedule, Lesnar has been at Raw pretty much every week for the last month or two and has also been appearing on some house shows as of late too. It is expected that this trend will continue for the next year.
Source: Wrestling Observer Newsletter