1. I doubt mankind will be around another 400 years let alone 4 billion. The smaller the world becomes the more convinced i am that it is our destiny to destroy ourselves
2. It takes roughly 8 and a half minutes for sunlight to reach earth, going on the assumption that her supernova would take a similar time to consume our planet... well... if the missus is cooperative, i for one can get a hell of a lot done in 8 and half minutes and the end shall come at roughly the same time that i do.
3. if the 4 billion year estimate is even remotely accurate... well, you could set this planet on fire and roll it into a black hole and my emotions on the matter wouldn't amount to two turds in a rusty bucket