My considerations about this are much more practical and about "game design" and feel.
I think with "local hyperdrive", braben really just means the mechanic used in elite 1. You know, the one where you get "mass lock" if close to any other body or ship.
This avoids escaping battles via "local hyperspace".
But there still are a bunch of questions open:
1. In elite2/3, inter-system travel cost and time, was an important aspect of calculating mission cost and if you could do it in time. How will that translate to E4? Surely, there should be a cost associated with traversing a system, because else the whole economic aspect of "profit for distance" becomes quite distorted, yes? If so, i'd expect "local hyperdrive" to consume a lot of fuel and NOT be "near instant".
2. Purely aesthetically, the time it takes to traverse a system, implies scale. If you can with just one mouseclick go from pluto to earth instantly, that severally reduces the feel of "scale" of space travel. On the other hand, we really do not want to wait 3 ingame weeks, just to reach earth. What i'm hinting at is a balance between the player falling asleep in intra-system travel, and any effort of intra-system travel seeming peanuts. I do NOT think, that such a compromise CAN satisfy "action" players. The speeds and times "action"-players would expect, would ruin any sense of "scale" of systems. Even if we were to assume, that "local hdrive" can take you from pluto to earth, in 1 minute (which really is very low, especially considering #3 below), some impatient players will complain about space travel being boringly slow.
3. Ambushes and interception. Given the sheer scale of a system, obviously it will be impossible to rendevouz with a ship (for whatever reason) via manual controls. With those large spaces, it will be impossible to "hit" a ship somewhere in the system, via manual steering. So, it has to be computers doing the rendevouz-control for you: You designate a target that is to be "intercepted", and the computer does the steering. Okay, fine - but imagine this: Lets say, you are employed among the police forces of a system. You are currently deployed around earth. Now some notorious criminal jumps into the system. First consideration: You can only "intercept" him in mid-space, if you have time to arrange for interception. If he were able to just "jump" to earth, no midspace interception could work. Okay, but just how much time will you get to set up interception? Notice that this depends on just how fast "local hyperdrive" is. Personally, i'd say "pluto to earth in 1min" is the minimum time-effort this "local hyperdrive" should take, to allow any strategic coordination. But as i wrote before: To some impatient players, even this 1min will be too slow.
TL/DR: It's all about the fuel/time effort of "local hyperdrive".... and i do not think that frontier dev will be able to make everyone happy here.