@12becca, no one knows! Most of us who answer questions here are volunteers. While there are a few who do work for EA, they either don't know the answer to that themselves, or if they do know, they aren't allowed to say anything yet.
However, it has been stated that the Sims 4 will last longer than TS1, TS2, or TS3 did. This lets EA have a stretched out timeline for releasing all the packs that go with it. That is why we are only getting one Expansion Pack (EP) each year (with 2 Game Packs (GP), and several Stuff Packs(SP) per year). So the end of TS4 is not near! Also, there isn't even a guarantee that there will be a TS5! But if there is going to be a TS5, it won't be for a while!
While the open world in TS3 was great in many respects, it was troublesome in others! For example, having a large open world would make the game run slower and slower as time went on especially if you had all the Expansions and Stuff Packs. Also, you would go to a venue at night and no one would be around at that venue and you would have to search the whole Sim world to find other Sims to interact with or complete tasks and wants. TS4 tried to combine what worked for TS2 and TS3 to give us something in between with semi-open neighborhoods, but now everyone wants TS3-style open worlds. But if we were to get those again, most people would complain how the game grinds to a halt!
Personally, my favorite thing from TS3 wasn't the open world, it was the Color/Pattern Wheel but I had so many pre-saved patterns that it took forever to load! This really bogged down my game. It was like eating dessert all the time; I really wanted it, but regretted indulging in it! LOL
I appreciate EA trying to solve these problems and think they came up with a pretty good compromise, but it is impossible for them to please everybody! (For example, I can live without the Color Wheel if they would just put more choices of color for each item. Some items don't have a green or red or whatever and it is hard to match! )
I am curious as to what they would do with TS5!
From looking back into all the release dates about every 4 to 5 years they release a new sims. So we are going on year 3 with sims 4 being out. in the next year or 2 are they going to make another sims game? I am just wondering.
@kirpaige13, I have heard some SimGurus mention that the run of The Sims 4 would be longer than TS1, TS2, or TS3. this makes sense since they are only releasing one Expansion Pack a year, unlike the other versions of the Sims. So, I wouldnt' look for TS5 to come about any time soon. Perhaps in another 3-6 years? But like @Phantomlover1717 stated, we don't really know!