I'm reading
The Sims Official Magazine and a few of the things they mention as being in The Sims 4 are:
- Timed career events, a la Ambitions
- A separate "Romance" bar to the relationship bar
- Clothes can cost money (simoleans, not actual money)
- Confirmed skills are Violin, Guitar, Hacking, Writing, WooHoo, Cooking, Gardening
- Sims can sulk in a bathtub while eating ice cream
- There are Whims (wishes) and Aspirations (Lifetime Wishes). Completing Aspirations gains an Aspiration Trait (ie, become a Master Chef = get a cooking trait).
- The crafting table, the voodoo doll, the cowplant, and the telescope are all returning
That's all I can see relating to TS4, but the magazine is an excellent read anyway.