I'm with the others who say don't break it up.
Sure, it's silly to have one rank in knowledge local because you know about the area you grew up in and suddenly, when you get to a city in a neighboring kingdom, you get to roll there too. On the other hand, it's just as silly that the skill necessary to disarm a complex magical proximity and alignment triggered trap (disable device) also works to place a flaw into the girth strap of a saddle so that it breaks after five miles of riding and dumps the rider on the ground. And it doesn't make much sense that every theologian (high knowledge religion) is also an expert upon the vulnerabilities of undead (also knowledge religion). Nor does it necessarily make sense that everyone who has studied the names and orders of the celestial host (knowledge planes) also knows the minutia of Mechanus and the ethereal plane.
In fact, this is even true of physical skills. Why every ranger who can hide behind a tree is also adept at following people through crowds without being seen (shadow application of the hide skill from Song and Silence) is unclear. Similarly, every skilled tracker is also a good hunter and survivalist and vise versa (since wilderness lore/survival covers both tasks).
Any attempt to overhaul the skill system that stopped with knowledge (local) would not go nearly far enough to succeed in making the skills make sense.
The skill system is meant to cater to the needs of adventurers not to accurately model everything that could go into it. Adventurers are equally likely to need to know about the depths of Hell as they are about the deep ethereal or the shadow planes. And they can't afford to ignore the Yugoloths and other less-well-known planar races because they're not as pretty as Angels. Similarly, adventurers will probably have cause both to sabotage equipment and to disarm traps. And they need knowledge of undead at least as much as about theology.
And that's probably the way it should be. (With ad-hoc circumstance modifiers, etc for familiarity with the location, etc and possibly permanent circumstance modifiers for an area of specialization (+2 for Angels/-2 for Yugoloths or +6 theology/-6 planar creature identification). In addition to being designed for use by adventurers, the skills are also balanced with usefulness in mind. Knowledge (Wintershiven) isn't too useful for a character whose travels take him from Greyhawk to Sunndi and to the lands of the Frost Barbarians on a regular basis--certainly not useful enough to crowd out skills like concentration, survival, spot, listen, tumble, etc. If it's to be useful even in comparison to jump, swim, etc, it needs to cover a fairly wide area.