I'm sure there will be some games that might not be completely compatible with this but as an optional setting that doesn't seem like a big deal to me. I'm also very sure it would be difficult to implement but I find it hard to believe that it would be a mess (in regards to per-game hacks etc) or impossible to implement at all. With Emulated Wii Remote there's already options to use an analog stick to update the IR camera's position incrementally. The augmented pointing thing would be more complex than that but still similar in the respect that it's preprocessing data before it's sent to the game and really shouldn't be any less compatible.
As for the games processing the data themselves, I don't see why that would be a huge issue. The modified IR data wouldn't be giving the game any data that a real Wii wouldn't be able to give it nor would it be in any strange structure. If the pointer goes off-screen it would still give it the same data that a normal Wii Remote would. The only difference is that if a point's X,Y position data disappears due to obstruction when the points is only half-way down the screen, it would be able interpolate the missing position data using the IMU until the point(s) is visible again.
As for the games processing the data themselves, I don't see why that would be a huge issue. The modified IR data wouldn't be giving the game any data that a real Wii wouldn't be able to give it nor would it be in any strange structure. If the pointer goes off-screen it would still give it the same data that a normal Wii Remote would. The only difference is that if a point's X,Y position data disappears due to obstruction when the points is only half-way down the screen, it would be able interpolate the missing position data using the IMU until the point(s) is visible again.