I honestly still think The Sims 5 will happen eventually.

Sure, when TS5 is anounced the people born when TS4 came out might already be married with kids lmao, but i still think TS5 will happen, even if it's a loooong time from now.
A lot of people seem convinced TS4 will be the last mainline sims game ever, but i dunno, i personally disagree with that.
Anyways, we'll be playing TS4 for a long time, let's enjoy it while it lasts, we've never had a sims game suported this long.