I don't like this logic.
If people assume Brock can't be realistically beat by anyone after what happened at Summerslam. They are assuming that every wrestlers that faces Brock will have the same "gameplan" as Cena (go straight ahead against the Beast).
Wrestling is way more complex than "Wrestler A destroyed Wrestler B (the biggest in the company) therefore no one will buy anyone else beating Wrestler A". Nah man, there's tons of ways of working around that.
You can sell the idea of Bryan (or whoever ends up beating Brock) having a strategy Lesnar, because he's a cocky motherfukker, didn't see coming and didn't prepare for. Then you have the beast playing catch up.
You can have Brock land awkwardly on his leg and his opponent taking advantage of it.
You can have a hardcore match were weapons even the playing field.
Brock is a beast, he is not god. You can book and make any wood wrestler work around a beast, doesn't matter how dominant that monster is.
I feel you but Daniel Bryan is not that guy. Neither is Roman Reigns. The reason WWE is in a corner is because I don't care what you say no has been booked to be better than John Cena. Yes Punk beat him somewhat cleanly, yes Bryan beat him cleanly but Cena is without a doubt best WWE has to offer. So to think that anyone on the present roster is capable of defeating Lesnar other than Cena at this point is not something I can get behind.
From what WWE showed at SS Brock is impervious to pain. So your telling me that Daniel Bryan can muster up enough offense to make Brock feel pain? Then take the beating Brock is gonna dish out? That's why I say WWE went overboard with his dominating victory.