if you are very confused, i'd recommend going back and re-reading. there are tons of ways the author shows that they are in the near(ish) future. yuuna's phone for example. or the city scape outside chiaki's hospital room, in the flashback.
we know that there was a war years ago, and that's when ponko was made. after the war, humanoid robots were no longer produced, hence the mechazawa looking guys. the whole "turn ponko into 500 yen coins" thing seems to be the government's way of slowly rounding up the last of the humanoid robots. was there some issue with them during the war? are ponko's struggles as a maid related to the fact that she was formerly a military robot? i mean, she has a black box and an arm cannon. were androids part of the reason for the war?
glad everyone is enjoying the chapter, I can't wait to work on the next one!