[gremlin]

A prequel would be neat, but what would they do?
If they did a sequel they would have to make it during the next cycle, or something, create a new threat and new characters and what not but it'd be the same races ( with maybe some additional ones that were discovered over the years ).

[Alpha]

Prequel could be showing the Protheans story perhaps, since they are the only other significant race known at this point who fought the Reapers. Or, could focus on Humanity's first contact with the Council Races (possibly First Contact War).

Sequel could be interesting....but would require greater work on their part in creating "new" lore.

[gremlin]

They'll have to work really hard to make the fourth game very successful and not a utter mess.

[Alpha]

That they will.....especially since there is still uproar over the ending to 3, even with the changed ending.

[gremlin]

I like the endings, it's just that it was executed poorly. I feel as if they had something grand planned but underestimated the time and effort needed to implement such a thing into the game. And it game out not the way that they in envisioned it to.