[Goldengreg]

Since I've always worked on entertainment areas (I was in videogames, now I publish mangas) I think I have an edge about this.
(haha, I'm talking like I'm actually briefed by Hasbro )

First of all, I would continue 3.75 line but would try to get it more gimmick-y.
As they did with the collectible shields of Secret Wars, or the chips of the japanese Avengers Disc Wars toys.

(the discs are used in a Heroclix-like game)

I wouldn't go to these kinds of plastic chips because they're costly to produce, and would draw a lot of hate from the fans.
What I'd do would be much more of a collaboration with Freemiums videogames like Avengers Alliance.
When you buy an MI figure, you have a unique code in the package. And as in Skylanders and the others, when you buy the fig, you get the very same character (or an item) in-game!

And in a second time, I would re-position 6" scaled figs for adult collectors with more parts and options as they do in Japan, with a lot of hands, faces, etc... (and if this doesn't work I'd come back to the BAF model)

Then, for 3.75" line, I would produce some henchmen troop-building packs as they did with G.I. Joe some time ago.

Like this...

...but with them!

And after that, I would produce additionnal items like Bandai does. Explosions, fire and ice effect etc... cheap ones for kids and pretty ones for display-loving collectors

Cheap ones

Pretty ones

But of course, that's what I'm saying as me.
If I or anyone else on this board was in charge of Hasbro, they would know the numbers... and unlike DVDs or Games, we don't know exactly how many sells what... it's the kind of critical info you need in order to build an effective strategy

best-selling figure ever! (?)