(Source:
Sims 4 FAQ)
This post is mostly just a heads-up that if you purchase items from the Sims 3 Store, and intend to upgrade to Sims 4, you might want to keep an eye on the amount of SimsPoints you purchase. According to the FAQ, the SimsPoints you have for Sims 3 will not be transferrable to the Sims 4 when it is released. Obviously, you don't want to be stuck with points you won't be able to exchange later.
The exacting wording is this:
Will I be able to use SimPoints to purchase additional content in The Sims 4?SimPoints will not be supported by The Sims 4, but will continue to be a form of payment for The Sims 3 content in The Sims 3 Store.
