New World? Or is it completed? New Game Mode?

I have recently completed the entire story mode portion of the game from ancient engulf to modern day. I have been wondering if PopCap will create new worlds because the ending was kinda confusing. Also PopCap should create a sandbox mode that allows you to create any size yard you want and allows you to choose which zombies approach your yard. It would keep the game fresh and I wont get to bored of just doing piñata parties everyday.

Trickster 555 about Plants vs. Zombies™ 2