Batman has historically stepped away from his vigilante duties as The Dark Knight by his mid-50s, which may be why he’s reconnecting with Dick, perhaps hoping that by helping him and his new team might convince Dick to return to Gotham to step into the Batman role in Bruce’s steed.
Dick has taken over before as Batman in the comics, although it’s not a mantle he’s stuck with.
It’s not necessarily advised, however, even for someone as fit as Bruce Wayne.