Mass Effect 4

We also know that the next game will go somewhere new and won’t star a character similar to Shepard, but this latest tidbit of information raises quite an interesting dilemma. If the team decide to pursue a prequel, they need to be careful not to conflict with any of the series' already-established canon, while a sequel would need to be set sufficiently far in the future that the varying endings of Mass Effect 3 don't create continuity problems, unless of course previous choices are once again incorporated as was the case between the original games.

It seems the team are aware of this though; earlier this month BioWare Montreal studio director Yanick Roy revealed that the next Mass Effect title "will be very respectful of the heritage built over the course of the first three games."