The only clues we get from the invite are the tag line — «let's take a field trip» — and the calligraphy - style Apple logo, which could hint at a new Apple Pencil.
The chamfered edges are matte rather than polished, the 6000 series aluminum has a stainless steel Applelogo inset on the back, iPhone 6s - style, and there's subtle SE branding beneath it.