Nice viewership. Brock leaving is obviously gonna have an impact. The opener should be huge since it was a combination of the fallout from the PPV, and Lesnar/HHH confrontation.
How I would do the whole Lesnar situation is something like this:
Summerslam- Brock comes back, and beats/destroys HHH, maybe making him tap after breaking (or nearly breaking) his arm again. HHH gets in a little offense, but it's pro-Brock for the match.
Night of Champions- Brock gets his rematch with Cena and beats him down again, but doesn't toy with him as much and ends up beating him.
HIAC- The rubber match between Cena and Lesnar. Lesnar beats Cena again, but Cena gets more offense in on this match than any of his others. Still, he loses relatively clean.
SVS- This one's a tough one if they do Cena at NOC and HIAC. If they don't do the NOC match I suggested, they do HIAC and then this would be their rubber match. An ironman match? I think it could work. If he doesn't face Cena then maybe CM Punk, but Lesnar would have to beat CM Punk and I'd assume it would be for the title. If it's not it's fine that Lesnar beats him with Punk getting in more offense than Cena or HHH. If it's for the WWE Title, then it's a tough one. I think we could make two branches out of this. One of them is Lesnar beats Punk in a non-title match, and the other is Lesnar wins the title from him.
If Lesnar wins the title:
TLC- A rematch with Punk. Due to the nature of the match, Punk doesn't have to fight Lesnar head on like he might've at SVS, and could utilize all of the weapons in the name. Lesnar ends up winning, but not without having his hardest fought match to-date.
RR- Feed Orton to Lesnar, simple as that.
EC- Lesnar wins EC.
The next night on Raw, Rock returns and confronts Lesnar, bringing up the point he made the night after WM28 that he wants his vision to come true, and thus Rock vs. Lesnar is made. Hell maybe Rock could win the Rumble in a surprise appearance. I don't know.
WM29- Rock beats Lesnar and while Brock still shows his dominance, it's not quite as easy as it was with Cena at ER. Rock comes back and beats Lesnar after a Rock bottom People's Elbow combo.
(This is the path I prefer they not take, as I don't want to see Lesnar/Rock for reasons already explained, but I put it here as an option for those who'd like to see something like this)
(This branch is where Lesnar beats Punk, but it isn't a WWE Title match due to Punk not having the title).
RR- Lesnar is a surprise entrance and wrecks through everyone. Hell, if they want to do something very interesting have him eliminate everyone else before #30 comes out. #30 comes out, and it's Rock! After an epic mini-match with Lesnar he eliminates him, wins the Rumble, and goes onto face CM Punk for the title, which at that point or by Mania at least will be regained by Punk. Maybe for Lesnar to keep his credibility up, they make it a point to have him be one of the first 10 entrants so by the time Rock comes out at 30, he's exhausted and Rock can go toe to toe with him believably while Lesnar keeps a superhuman image.
EC- Brock becomes a participant in the chamber, and is the last one. No one else is eliminated before Lesnar comes in, and when he does. The 5 guys stop, surround Lesnar, and beat him. Each hit their finishers before eliminating Lesnar once and for all.
Lesnar at this point is fed up and realizes he's already become champion, he beat Rock back when he was a rookie, he's beaten Cena, he's beaten HHH, he's beaten the current WWE Champ CM Punk, he's beaten Orton, and there's no one left for him to face. Think Rock's promo from 2003 where he said he was leaving, and before he has a chance to leave the ring, *GONG*. Lights go out, Taker comes out, and tells Lesnar there's one thing he hasn't done. One thing no one has done, and one thing he can't do. Beat Undertaker at WM. From there on out they can build up the fact Lesnar has beaten and destroyed Taker in the past in his own match of HIAC, but that Undertaker at WM isn't the same Undertaker you see (or don't lol) the other 364 days a year. They could though play up the fact Taker has never been able to beat Lesnar one on one.
WM29- This will be very similar to Taker/HHH WM27. Taker will get mandhandled by Lesnar most of the match. At the start though Taker does go toe to toe with Lesnar, hits his signature moves, chokeslam, last ride, old school, etc throughout the match. Lesnar eventually starts to overpower and beat down Taker. Throws him around like a ragdoll. However after numerous F-5's and Taker kicks out of all of them, he finally pulls out the same submission he used to injure HHH and Cena, and made HHH tap out with at Summerslam. Taker's arm seemingly breaks, he passes out, and the ref almost calls for the bell but Taker gains life and somehow (I'm not sure how) reverses it into hells gates. Lesnar power bombs his way out of that like he did to the triangle choke at NM03. Lesnar brings in a chair and places it down. He then picks Taker up for one final F-5, but Taker somehow manages to counter it into a tombstone piledriver. He spike-tombstones (like he did to HBK at the end of WM26) Lesnar and doesn't even do the darkness pin, but just falls on top of him for the 1-2-3. Lesnar has to be taken out on a stretcher and he can be written out for good due to neck problems from that tombstone on the chair, while Taker may or may not be wheeled out as well. It'll be a bit more decisive win for Taker than his WM27 match if he can at least limp out in some way, so he doesn't come begging for a rematch with Lesnar at WM30.