Based on his comments, not only will Infinity War and Avengers 4 branch out into the cosmos, but in doing so will introduce multiple new locations.
Thanos will be coming to this planet in Avengers: Infinity War and the followup Untitled Avengers, but the entirety of this epic team up will (thankfully) not stay on Earth.
Throughout 14 films, Marvel Studios has made one thing abundantly clear, the Earth is the central planet to their universe.
Not only have 11 of the movies solely taken place on Earth, but both of the Thor films are majorly involved on the planet.