[cheebacheeba]

Hm...yeah "Age of Ultron" the comic series would not make a good movie.
VERY convoluted, not to mention takes place with different characters, a different set of avengers that have
a: Not been established in these films at all yet
b: Been X-Men
c: Been Fantastic Four members
...The last two there won't happen due to current fox ownership of those...
If they tried to spin it differently with different characters, no, I just do not see it working. It's definitely a storyline that would take more than a movie to do it justice, and yes...too many variables....

Though something involving the creation and ascent into sentience of Ultron would be good.
They could potentially do ONE reality shift for part of the film (VS the ?5? in the comic series) by having Ultron somehow contact his future self, or a future self simply coming into existence after his creation...who would go into the past to assure his creation/ascention which would fuck with the current timeline.

Then I'd assume the Avengers of that "warped" reality would somehow gain access to the time shifting technology and go back to our current time as seen in the MCU thus far, and be working counter to Ultrons intentions.

Perhaps they could even be at odds with the existing Avengers.
I don't doubt there will likely be two versions of at least some of the core characters.
That would actually work, as long as they didn't tie it in too many knots.
Ultron is a GREAT villain.

...Too bad though, I still wish for Kang the Conquerer.

If you thought that idea seems a little convoluted to work, well...the comic would be tenfold of that.