I’d say that the shot in the tweet looks a lot like a planetary landscape of some type but that seems a rather obvious ploy. I really think that looks very much like rebar on the left. Plus, as I said after I saw Homecoming, the only reason the MCU powers that be had to have Tony evac the Tower out of the clear blue, and for no good reason was so the Russo’s could use it as a finale set piece explosion in Infinity.
Also, Feige said that Infinity and the movie-to-be-named-later (Disassembled is my guess) would both be full of comic references.
So, that’s my thought on this tweet.