There are several family lineages and storylines that span multiple games in The Sims series. These lines can be used to create a rough timeline of events in the series.
Generally speaking, the events of The Sims 3 occur the earliest in the in-universe chronology of the series, followed by the events of The Sims and then The Sims 2. For example, Bob Newbie and Betty Simovitch appear as teenagers in The Sims 3, are married in The Sims, and have had a child and have died by The Sims 2. However, there are several instances (especially with The Sims 3) where events do not seem to agree with the in-universe chronology. There are several player theories which attempt to resolve these discrepancies, as well as some canonical alternatives, such as time travel in The Sims 3: Into the Future. The Sims 4 does not follow the in-universe chronology of the series, but does have some returning families, making it seem like an alternative universe.
Every one of The Sims game takes place in SimNation. In the series, SimNation is shown to be set around the 1990s, 2000s, or possibly even further on. An official interview with Bella Goth shows that she was abducted in the summer of 2004, meaning that The Sims 2 is probably set in or after 2004, placing The Sims 3 in 1954 and The Sims in 1979. It shows modern, real-life technology such as TVs, cars, and computers - but also some futuristic, advanced technology such as Servo[TS:LL][TS2:OFB] and the Teleportation Pad[TS3]. The locations of The Sims games could be anywhere in the world, or even in a completely different universe altogether.
When trying to construct a timeline such as this, order of events often has to be inferred, or outright guessed-at, so the list for any period may not be in exact chronological order. Regardless, below is an incomplete timeline of the entire The Sims Series.
Although the future of The Sims is left up to the player's imagination, some things are very likely to happen, as The Sims 2 has already "set the stage" for them.
Please note that these events are not confirmed by EA and are purely speculation!
Here is a list of events which could possibly happen when The Sims 2 for PC lets the player take control: