Four of the images reference the Canada's CN Tower — the world's largest free-standing structure. Fans are speculating that this suggests Hitman 5 will be set in Canada.
It's the fifth image that is most interesting though. It looks to be a screenshot from a CGI movie, showing a silencer being applied to a pistol.
IO Interactive's said that the ARG is over now, and that the game will be announced at E3. You've got a couple of months to wait yet then.