As I see it there are 2 issues.
First, in addition to wear and "being in use" damage, the older material seems to have many quartersawn pieces, whereas the new does not. The newer oak also has boards that would not have been attempted 60 or more years ago due to today's lumbermill technology. So the first step in matching is to make the newer stuff look more like the older stuff, independent of color.
That could involve everything from adding nail holes at the end of boards and gouges into high wear areas, sanding quarterround (or quarter circled) scratches into the floor under closet doors, intentionally wetting areas nears doors and windows to get a darker look, etc.
The second issue is the color. Without having to sand everything down, the only thing I can think of is a toner. The problem with a toner in a situation like this is:
1) you'll need to find a finish that's A) compatible with the existing finish and B) capable of adhering (a strong bond will be needed) to the existing finish
2) to get the color right you may have to apply multiple coats of toner, which may give the floor a muddy look,
3) you'll need to apply at least 3 coats of finish. With this many different coats of material the risk of a coating breakdown increases over time.
I hate to be pessimistic, but that seems to be a lot of work (and some risk) though I completely understand the point about the island (and from experience, having to tell your wife the kitchen will be a work area !)
I think that for the same effort, you could remove the existing finish. I know this isn't what you like to hear Rich, but the right way usually doesn't have too any shortcuts (though just like you, I'm always trying to find them !) If you go this route, once the finish is removed, you can perform whatever distressing you think will add to the overall appearance (including adding color variations).
Hope this helps.
Bob "Boardman" Borders