This is basically my thoughts. The story was self contained and finished (poor ending or not).

Only thing I can see them doing is maybe game based on First Contact War. You are a leader in it and play your part, so a prequal. Whether stand alone story orMMORPG, doesn't matter (although I'd prefer the former).

I don't like the multiplayer, and it should have NEVER affected the main single player story, that a stupid idea that was. This said, they should include in a single player game the option to 'help' people out while doing the same missions, so up to 3 players playing co-op at a time on different missions. If no co-op you have your normal squad mates.

With the Extended Cut DLC, multiplayer wasn't needed overall galactic power level didn't need to be as high to get all the endings. 

I enjoyed the multiplayer but i would prefer opt-in co-op, the game completely lends itself to it. 

I still have to get and play the third game, but giving the reactions of the people and where EA seems to be going (games that need to sell +5 millions to be successful), I expect even less focus on the RPG elements and more focus on the shooter mechanics.

And as others have said, lots of DLCs.

It still does though, I have 4 characters, one normal, one good, one evil and one useless. I played and finished the game with the first 3 before the DLC, I then didn't play for a while but had started the useless one, I finished the game recently with only 50% base readiness and it affected the end (characters died etc). Ignoring the fact I wanted this to happen, it still affected a single player game and if you bought the game 2nd hand, borrowed it from a friend or any number of things, you'd only ever have 50%. Multiplayer should not affect single player like this.

Co-op would be great.

i would like to see co op in the main story like having a friend play as a squad mate or perhaps bring their character over and have them become a squad mate in your game and can have a romance with them

have at least as much exploration as mass effect 1

space combat

have your choices matter

keep the combat the way it is in mass effect 3 but amp the RPG elements in just everything else to 1000 and

give a bigger focus on squad commands

After three games I am really tired of Mass Effect. I just want a space game where I can fly around and shoot things.. Mass Effect mixed with x-Wing and space ship battles sims would be day one.

Gameplay of Mass Effect 3, characters of Mass Effect 2, story like Mass Effect 1. With next gen graphics ofc.

A story line that puts you in the shoes of the Reapers and the Geth would be cool. For me there did not seem much difference between Mass Effect 1, 2 or 3. You choose different options in ME/2 but get the same generic empty Mass Effect 3 ending. ME3 was rushed and a huge let down to the entire series.

more particles

Very, very low indeed, seeing what Bioware have been serving up lately.