As far as how long I actually think we'll be here based on the direction and action of mankind then not very long especially with nations like North Korea and Pakistan possessing Nukes, Russia running a stealth cold war with an ex-KGB control freak at the helm installed as dictator. Egypt, Libya, Tunisia, Turkey going the same way as Iran did in 1979. Replace one dictator and get in a bunch who are a whole lot worse. Syria could go either way. If they overthrow Assad they will probably get someone a lot worse. Iraq could go either way. So far they have also chosen to ally with Iran and again take the wrong path. Iran the big problem a state sponsorer of terrorism worldwide, with mad mullahs running the place about to go Nuclear and quite prepared to sacrifice their entire nation to wipe out countries like Israel, America and Britain.
In short I believe the next 230 years we will see a whole lot more turbulence and trouble, then we will see 1000 years of peace when Jesus reigns as King of kings and sets up his Earthly throne, followed by the complete destruction of this Earth and the entire Universe.