http://tvline.com/2018/05/10/last-man-on-earth-cancelled-season-5-fox/

Will Forte's Fox comedy will end with last Sunday's cliffhanger season finale. January Jones announced (https://www.instagram.com/p/Bim-aUYlsdA/) the cancellation news (http://forums.previously.tv/topic/53785-last-man-in-the-media/?page=3) on Instagram, saying: "To our @lastmanfox family..it’s been an amazing 4yrs, thank you for all the hard work, we love you and will miss seeing you every day!" In an interview published earlier this week with EW, Forte said of the decision to end Season 4 on a big cliffhanger (http://ew.com/tv/2018/05/06/last-man-on-earth-season-4-finale-will-forte-cancun-baby/): "If we got a fifth season, we’d probably be thinking that was our last season. Early in the season, we were thinking, 'Oh, let’s try to find a way to wrap it up just in case.' And then we thought later, 'Let’s not put that pressure on ourselves. Let’s just write a good episode and try to do what we do,' because we didn’t want to make it easy on them. If they want to cancel us, that’s fine, go ahead and cancel us, but we’re not going to put a little bow on the show for them."

Will Forte's The Last Man on Earth cliffhanger ending was actually the perfect sendoff (http://www.vulture.com/2018/05/last-man-on-earth-ended-perfectly-even-with-a-cliffhanger.html)
According to Jesse David Fox, Forte treated nearly every episode as a series finale. He adds: "When the news of cancellation came out, I emailed Forte’s team, asking if he wanted to reveal how season five would’ve started. But in the time since (and because they said he was unavailable), I’ve decided that I don’t want to know. Because that uncertainty is at the core of the show. We’ll never know the fate of our main characters because there is no way for them to ever know their own fates. Almost every single episode of Last Man on Earth ended with a cliffhanger, partly to get people to keep watching, and partly because that’s truthful to the story they’re telling."

Will Forte thanks Last Man on Earth fans: "It was an experience that I’ll cherish forever" (https://twitter.com/OrvilleIV/status/994930130911940609)
"Sad news yesterday," he tweeted this morning. "As many have already heard, the show is not being brought back for a fifth season. On behalf of our little family, thank you for all of your support."

Will Forte is still hoping to give The Last Man on Earth a proper ending after its abrupt finale in May 2018 (https://www.thewrap.com/will-forte-last-man-on-earth-ending-revival-macgruber-premiere/)

Even though Forte already gave away the ending, he still has hopes to give his Fox comedy a proper finale. "If we ever get a chance to do it again, who knows, maybe we would do it differently,” Forte tells The Wrap. “Or maybe it’s a long con. Maybe I did a bait-and-switch.” He adds: “We still have, like, if we got a chance to ever revisit that and try to close it, we have no idea how we would do it. So in a way, I was happy that they canceled it, so we didn’t have to figure out how to end this thing. It would just be so, so tough. I mean, I have so much respect for shows that are able to have these great endings."

I discovered this show and watched it during the original airing of the second season and beyond. Reading about some of the stuff they'd planned on doing for Season 5, it was probably best it ended when it did. Hopefully if they ever do decide to do something to give it an ending, they scrap that talking cat idea.