Just in case no one has seen what BioWare have actually said about the EC so far, with my bolding:
Here is a mini FAQ to help you understand what the Mass Effect 3: Extended Cut is and isn’t:
What can fans expect from the Extended Cut DLC?
For fans who want more closure in Mass Effect 3, the DLC will offer extended scenes that provide additional context and deeper insight to the conclusion of Commander Shepard’s journey.
Are there going to be more/different endings or ending DLCs in the future?
No. BioWare strongly believes in the team’s artistic vision for the end of this arc of the Mass Effect franchise. The extended cut DLC will expand on the existing endings, but no further ending DLC is planned.
What is BioWare adding to the ending with the Extended Cut DLC?
BioWare will expanding on the ending to Mass Effect 3 by creating additional cinematics and epilogue scenes to the existing ending sequences. The goal of these new scenes is to provide additional clarity and closure to Mass Effect 3.
When will the Extended Cut DLC be available?
Currently the Extended Cut DLC is planned for this summer, no specific date has been announced at this point.
Why are you releasing the Extended Cut DLC?
Though we remain committed and are proud of the artistic choices we made in the main game, we are aware that there are some fans who would like more closure to Mass Effect 3. The goal of the DLC is not to provide a new ending to the game, rather to offer fans additional context and answers to the end of Commander Shepard’s story.
Will there be more Mass Effect 3 DLC?
More content is being planned and we will release information at a later date.
So there you have it. Are we proud of the game we made and the team that made it? Hell yes. Are we going to change the ending of the game? No. Do we appreciate the passion and listen to the feedback delivered to us by our fans? Very much so and we are responding.
Summer is coming…
"Extended scenes that provide additional context and deeper insight to the conclusion" could certainly include some tweaking to the existing gameplay at the game's conclusion (and therefore, new gameplay), likely just more video and conversation (which is what the ending is all about), but the correct additions to those conversations could go a long way to clearing things up. This could equally just mean more video alone.
"Expanding on the ending by creating additional cinematics and epilogue scenes to the existing ending sequences": For gameplay, this doesn't seem to leave a lot of room. I guess a surviving Shepard might get a bit like at the end of DAO where he gets to speak to his friends. But expanding on the ending is entirely different from changing the ending, so whatever happens we're not likely to get the chance to do much different, just get a better sense of the results of our actions.
Speculation, of course.
What's not speculation is that data direct from BioWare is not "misinformation"; along a few vague hints from voice actors, it is the only information we have, and to dismiss it does not make much sense.