Moving the Tesla announcement to Wednesday. Needs a few more days of refinement. — Elon Musk (@elonmusk) October 16, 2016

Tesla also has a SolarCity event on October 28th, and will show off integration between SolarCity and Tesla products. It just revealed that it's partnering with Panasonic on solar panels that will be used in conjunction with its Powerwall, provided the SolarCity merger is approved. Given that, it seems likely that Tesla's "unexpected" product will be home energy or battery related. One of the last times Tesla teased something, it went on to launch the PowerWall home charging product last year.