Yeah, I don't see it coming soon at all. I definitely think it's in the making, but with the intricacies of modern gaming, plus the complicated layers of tech required to make a Sims game, I think it will take a while. Maybe we'll see an announcement by end of next year, but it will be premature while the game continues to be developed for another year or two, at least.
Maxis has been saying "more years to come for Sims 4", and I have no reason to doubt that, since the fiscal reports keep saying the revenue is increasing and they just rebranded last year, which is like starting over. They're not going to rush Sims 4 out the door as long as it's bringing in the money. Plus, they're still adding to the Sims 4 team. They just hired at least one new QA person to help iron out the bugs.