If Spongebob sets are returning in 2019, here are my set ideas.
Conch Street 4 Minifigures: Spongebob, Patrick, Squidward, and Gary Spongebob's Pineapple, Squidward's House and Patrick's rock. Bigger Squidward House Patrick's Rock in brown Price: 49.99
The Krusty Krab
6 Minifigures: Spongebob, Mr. Krabs, Squidward, Plankton, and 2 customers
4 Tables
Full exterior
Patty Wagon
Price: 29.99
The Chum Bucket
4 Minifigures: Plankton, Karen, Spongebob (Wall and physical) and a robot
2 Tables
2 Floors (Food area and lab)
Jerk Maker 9000
Price: 39.99
Sandy's Treedome
3 Minfigures: Sandy, Spongebob and Patrick
Picnic Table
Bird bath
Exercise Wheel
Tree
4 Animals: Ant, Worm, Butterfly, and fly
Price: 79.99
Jellyfish Fields
2 Minifigures: Spongebob, and Patrick
10 Jellyfish
Jellyfish Fields Sign
Price: 9.99
Boating School
4 Minifigures: Mrs. Puff, Spongebob, and 2 people
Building and Lighthouse
2 Boats
Full class exterior
Price: 59.99
Exclusives:
Flying Dutchman's Ship
4 Minifigures: Flying Dutchman, Spongebob, Patrick, and Squidward
Full exterior
Can Float on water
Price: 99.99
Mermalair
8 Minifigures: Mermaid Man, Barnacle Boy, Man Ray, The Dirty Bubble, The Quickster, Captain Magma, The Elastic Wasteband, and Miss Appear
Computer
Invisible Boatmobile
Time Machine (From Back to the Past)
Price: 109.99