With that in mind, I've been lead to believe that Mass Effect 4 is very much, through and through an entirely fresh, new chapter. While big fans like ourselves will naturally question where it occurs in the canon and how it can be tied in, most games like what Mass Effect 4 will likely be do not aim to appease this crowd. Yes, it's the fourth game in the series, but it also might as well be an entirely new entry point for people who've no clue what the franchise is about. Built in such a way that prior knowledge of the series is barely relevant. The fact it is unlikely to be called "Mass Effect 4" is an example of this, much in the same way Human Revolution was not called Deus Ex 3 nor required or demanded series familiarity to enjoy.
...Mass Effect 4 won't be "Mass Effect 4, the continuation of the Mass Effect universe that requires or supplements knowledge from the Shepard trilogy". It'll be a completely fresh start, and it would be unusual for a publisher to push out a content pack limited by last generation design within a 12 month window of a game that will no doubt be pushing the future of the series first and foremost.
Without the 'relays' the trilogy could've easily been called something else. They were canon, and without them I'd like to think that pivotal events would never have taken place. With that said, assuming relays and every sentient species in the galaxy remains dependant upon them, I wouldn't knock a numerical naming convention for the next one. I'm expecting the franchise name to remain obviously, but something colonic - grammatically.