I think that the next game is going to be about the construction of another Mass Relay.
It doesn't make sense that if they had a standby that they would use the Second Mass Effect to just tell about a Huge Reaper and a recruiting process if there was a Second Relay some way. They said at the end "we'll find another way" not we have alternatives.
What Harbinger had the Collectors doing and what the other Reapers were doing aren't mutually exclusive activities. Nothing about building a human Reaper does anything to get the other Reapers back from dark space and so it's failure wouldn't directly impact any endeavour to that end.
When Harbinger actually said was: -
"Pathetic human. You've changed nothing. You have merely attracted the attention of those infinitely your greater. Those you know as Reapers shall be your salvation through destruction. You have failed. We will find another way...releasing control."
It's all there. Stopping the Collectors didn't change their plans, just caused them to target Earth first.
I suppose it's also possible "You have failed. We will find another way...releasing control."
was all directed at the Collector general rather than Shep, but it makes little difference either way.
I'm pretty sure that last bit was directed at the Collectors.
It seems clear to me that whatever the Collectors were doing with that absurdly large cyborg it had something to do with another relay.
Clearly Shepard had already attracted the attention of the Reapers when he stop the first Geth Invasion of the Citadel. They hunted down the Normandy and attempted...(shrug) consume? Sheppards body for some reason like he was special or something.
I got no sensation of a Grand Plan in the 2nd Mass Effect it was all Exposition and Recruiting which to me is just an extention of the First Game.
If they already had that Mass Relay they would have used it in the two year interval...clearly they had plenty of minions to activate it...the Geth and Collectors combined. Infact I find it rather odd that the Collectors weren't part of the first invasion....makes no sense. It would be lame to do another...lost relay...they've done it twice now and to go back to the same barrel...would be flat after what they achieved in the First Game.
No..it only makes sense if some where another mass relay is being built. It's like the Supergate from Stargate. The First Gate was pure miss direction, the second gate was built elsewhere away from the Milky Way's attention and from there a Beach head was established. Remember these guys built the Mass Relays...they can build another when ever the wish.
One things for sure...I could never see how the Galaxy could survive if that Dark Relay gets built and the Reapers come through. It would have be limited somehow...I mean we're obviously building up to a climatic end where huge fleets will be needed both ground and Space....Either that means the Reapers are massing minions elsewhere or the Reapers actually succeed in coming through the Relay...
If that happens...
I think this will be one of THE Greatest Games in History.