I think reviving IN requires a new "elevator pitch" - the short description of what the game is about and the experience you get in playing it.
The original French game seems to have been blatant religious satire, to a degree that would never be acceptable in the US market. Derek Pearcy re-conceptualised it into a cold war between Heaven and Hell, and that succeeded because there was a strong interest in angels and demons at the time in Western popular culture, and the real-world Cold War was still recent enough to serve as a reference. But neither of those conditions apply any more.
IN is also a relatively difficult game to run IME. Not the mechanics, they're really easy. But creating a plot and story that lives up to the standard of all the cool stuff in the setting is hard work. Both the campaigns I've played in, and the one I ran, petered out with their grand themes unresolved. Difficult-to-run RPGs aren't what sells well these days.
So we need a new concept of the game, a new form of relevance to the players. Fortunately, there is a way to experiment with such ideas and develop them. The SJ Games
online policy allows running IN
Online Roleplaying Communities. If someone wants to do that - I don't have the time or the skills - I'll come along and participate.