I think they need to avoid casting someone infirm (so as to avoid the Harris/Gambon scenario from the HP films, but there's plenty of examples of older actor that are still up for regular gigs (Sir Patrick for instance is seventy-nine, but I wouldn't call him geriatric and Sly and Arnie aren't much younger and still kicking it).
Incidentally, given that the de facto age gap in the comics is about twenty years, and a sampling of past actors averages a gap of thirty to forty years between the Perry actor and the CK/Superman actor, then i'd argue that it's a disservice to the character and the history of the role to cast it as any younger than sixty for the new show.
Given that Tyler is 32 years old IRL playing a 40-year-old Superman, I'd personally rather they follow that same pattern with Perry White if he's going to be part of this show. Cast somebody in their 40s or 50s, but then write the character as being in their 50s or 60s.
That way, you're keeping things similar to the comics in spirit without hamstringing yourself from a practical standpoint.