The call came out and I answered... hehe...
If that's the precise wording of the sentence, than it means the REAL power of the system's connectivity. I've seen some pretty good examples of what this could be in my talks with friends:
1) Imagine an RPG where the battle interface, menus, and whatnot are ON THE GBA. The cube is complete immersion with no windows, numbers, or anything. Instead, stuff like the minimap and subtitles are displayed on the GBA, while the sound comes out of the TV.
2) In said RPG, the character dreams, which is only viewable on the GBA. Details from the dream could be used to find a new subquest or the like.
3) In games like Final Fantasy Tactics (NOT the game itself, but games of that style), saving characters and equipment to the GBA cartrige instead, allowing a connection to another GBA for battles or to another Cube in place of a memory cart. The idea is that you bring your party into your friend's file, he pays a price at a mercenary camp, and your party can show up in his next battle, to help him win it! Or, in games that use a system like Diablo's for making items (randomly), suppose you find all the stuff you need to make an excellent runesword, but are missing a mystic anvil or something, but your friend found one. Using this system, you can connect to your friends' game (while they visit as a travelling merchant in-game), and buy it off of them. You incorporate elements of a trading game like MMBN or Pokemon with elements from Diablo and MMORPGs -- while still having it a predominantly single-player game!
4) a 2-player mech-type game. Imagine one guy on the cube piloting the mech and figting hand-to-hand, while the other (on the GBA, which displays targeting data) coordinates with special attacks and lock-on targeting ("Mike! This one's fast! Lock on to the engine and see if you can jam it! I'll try to cut down those missle launchers!")
5) Find an item in an RPG that works like a translator. This item is mimicked in your GBA. You can't understand a word they're saying -- until you look at your GBA screen, which has a transcript! This same feature could be used to save and record conversations, replayable at ANY time (in a cutscene, for instance) since it's a separate game system.
The ideas keep coming up with themselves. My guess is it's one of these ideas. A game that truly exploits the connectivity between the portable system and the console. Most likely the disc will be sold with the GBA cartrige in the same package.
Just the desires of an old gamer... I'd think Nintendo's the right company for it, too -- they're powerhouses of innovation like this, and if anyone's gonna do it, they're it.
-Tempest out.-