At least, that's what the director told the writer of this article at CHUD:
http://chud.com/articles/articles/22433/1/CAPTAIN-AMERICA039S-INTERNATIONAL-CO-STARS-THE-INVADERS/Page1.html

It will be interesting to see what they do with this. On the one hand, it seems like doing this could push Cap too far to the sidelines of his own movie. Then again, imagining Cap in Wolverine's role screentime/importance in the first X-men, with Bucky taking Rogue's and the Invaders taking the rest of the X-men's time doesn't necessarily seem that bad to me.

It will be interesting to see what characters they can actually use... Speculation is that Namor may be under the Fantastic Four deal with 20th Century Fox, and one wonders if the Human Torch motif isn't locked up there as well, despite it being a separate character. (The idea that they could possibly still use Toro, as a Spanish character no less, is certainly interesting.)

Naturally, my thought is that if they're planning on using the Vision in movies at all, then they may as well set the groundwork here. They could introduce either one (if there's no Torch, then have Horton build the Silver Age Vision directly). Either way, if they introduce one, then that's the one they should stick with... The whole concept of a second Vision built out of the remains of the Human Torch, sharing the look and name of a mystical Golden Age character is needlessly Baroque for movie audiences.

So who should be an Invader on screen? Should they use the spots to introduce characters with spin-off or Avengers potential? Or go for true Golden Age characters that were actually Invaders?

Since he only made his Silver Age debut in the Fantastic Four, apparently some argue that he's not included in the Fox deal at all. (In fact, they were working on setting up his own movie at Universal, apparently.) If they're looking for a way to launch Namor with this movie, then I can understand... although I hardly think that the WWII ties are necessary for that character.

Namor and the Torch are such big concepts, however... how easily are they just dropped into a film? Looking back at my example above with the X-men, once you've explained the "mutant" idea, you can simply drop in as many bizarre powers as you like with no further context needed. I guess that the best I can imagine here would be having an early version of SHIELD (or just the OSS?) introduce Rogers to the idea that they have been gathering a team of unique individuals since before he became a super-soldier, just like Fury is apparently doing in "Iron Man" in preparation for the Avengers movie. I'd still think that you maybe couldn't actually get into the fact that Namor was king of Atlantis or whatever.

Since the interview mentions 6 Invaders, I'd say:
Cap
Bucky
Namor
Torch (some version, if they can)
Union Jack (or some other British operative)
A soviet operative (an earlier Black Widow?) to keep go with and "allies" theme and tie into the present.

I'm sure Nick Fury must show up in WWII at some point as well, with his Howling Commandos.

...since filming isn't all that far off, my guess is that they have a script they're ready to go with. According to the director, that script features the Invaders "all through the second half" or something.

You could be right to remain skeptical, seeing how the next Spider-man movie fell apart right around this point, but I think this one is going to pan out for better or for worse.