It is entirely possible that the reapers destroy organic civilizations right before they unlock the key to building mass relays and becoming if not as powerful as the reapers themselves technologically then for the reapers to have to chase them down from system to system and probably taking hundreds if not thousands of years. Hopefully that's not too much of a run-on sentence. This could be also why the reapers choose this point in their advancement to harvest them. The reapers know that the next big stepping stone is mass relay deployment.
So now, what does that mean for the next game? Hmmm. Well, depending upon when the game is set... It could be a thousand years or one year after Shepard's lifetime. So, we're gonna go with a basic one hundred year estimate. My thinking is this... The council races will have to have realized the dangers of opening new relays (Mu relay) and will only link star systems that they know are safe.
So that's what this could be... One hundred years after Shepard dies... Building (yet barely functional) a new mass relay to somewhere that has its own mass relays(except they're red and white, not blue and white) and they call them something different and that aren't linked to ours.
And that's what the ARKCON project could be... The three companies that Vaz mentioned conferencing and convening together to make an even larger profit because for each and every ship that passes through the relay a bit of back energy is produced powering the solar systems that are around it.
Hmmmm. Thoughts?