If fifth gen is really the reincarnation of third gen we're expecting, I would love to see Brendan make an appearance. For some reason, Brendan is one of my favorite male trainers despite his odd design (and hat) -- maybe it's because of how long I've been following Pebble Version, I don't know. In any case, to see Brendan or even May make an appearance in fifth gen would make me very, very happy.
I wouldn't necessarily mind if he surpassed Red either -- if they can pull it off without making it a grindfest, and they need to make his levels higher to advance the series in one way or another, I'm all for it. As much of a nostalgist as I am, and as much as I'm a fan of Red, it wouldn't make much sense for them to deflate the levels of a trainer to keep from surpassing Red, as Red will always be remembered fondly by us, highest leveled Pokémon or not.