I expect/hope they'll carry on the Sims 4 for quite a while longer, if they made another game what would even be different? The computers that Sims players have have barely improved since the Sims 4 came out, a huge percentage still can't even play 3 as their computers aren't good enough. So open world probably wouldn't be possible, improving graphics wouldn't be possible it'd just be a pointless new edition that brings nothing new. I hope they'll try to come up with some new and different pack ideas and carry the Sims 4 on for atleast 2-3 more years. At this point the rest of the occults (faeries, werewolves, possibly zombies) are the only expected packs so hopefully we'll get some interesting and unexpected stuff outside of the usual sims release pattern