The Orville was one of the last shows New Fox picked up this year. Since New Fox doesn't own the show anymore (Disney does), and has lost hours with WWE taking Fridays, they apparently gave MacFarlane a hard date he couldn't meet, so they dumped it. Recall that Season One had a huge hiatus since they couldn't get a back nine done in time and had to wait to the next season.
As far as the future, who knows. Ironically, the show is now owned again by the 'network' that airs it - was Old Fox / 20th Century Fox, now Hulu / Disney, and should be better protected. My guess is Disney demands some pretty significant cost cuts before okaying Season 4. Though given how difficult it is to get streaming numbers, you will never know for sure if its a success there or not.