I dont think any of the live action parts are really needed, but their not unwelcome either. The ending is long, but good. The Duplo invasion could be enjoyable. If they tie in all of the other knock off legos too, it could be very interesting.
Duplos aren't knock off LEGO's they're just LEGO's for younger kids.
I'm hoping to go see this later this week.
You are correct, I was thinking Megablocks, kenex, etc.
I do wounder if they could have an invasion of fake legos affect the town though.