Re: Avengers Sequel ideas?
Well, they're drawing from material that has this stuff in existence. Did vibranium show up before Captain America, no (yes it took place in the 40s before the other movies in the mcu timeline but it still existed). Stark created a new element for pete's sake. I don't think it's a stretch at all to introduce things we haven't seen for the first time into the movies. Especially when you're facing a ridiculously dangerous threat such as this. Of course it's not going to work, you're right, that's why the avengers were formed, but should that stop them from making the attempt? I don't think it should.
As far as Ultron being the enemy, I just think having three cosmic/otherworldly threats in a row seems a bit heavy handed. The Avengers handled heavy hitters on a domestic(earthly) level too. Yes not having pym rooted in the present could be a problem, but they could find ways around that if they wanted to (I hope to god not trust me). But we can agree to disagree and move on.
What we can agree on is that this movie is going to rock and they'll give us a great sequel to boot, no matter what they do.