Green creates a very large community of organic-synthetic hybrids with Reapers intact and working alongside them. Every other organic out there can easily be Reaped (especially since Catalyst is still around). That's why we won't be able to access the previous galaxy if Synthesis was chosen in ME:Keep.
The wave travels faster than FTL (catches up to the Normandy). It still has limits though.
Ships in ME are capable of regular FTL, even shuttles can do that (ME2). Relays provide a much faster means of travel and they are linking cluster to cluster. Traveling within the cluster is made by regular FTL.
Uhm, this was my point. That Bioware can make new ME game in that unexplored region of the galaxy and it will work for every ending choice.
I think you're missing the point. Yes, FTL travel is how ships get between planets in star clusters and relay transit is how you get between star clusters - no one is debating that. What we were pointing out to you (and you seem to keep overlooking) is that we only visit a few dozen star clusters in the trilogy. There must be literally millions of potential star clusters in the relay network, and potentially billions of accessible stars total (via FTL travel inside of clusters). Even if the network, which includes both relay systems and ALL systems accessible via FTL covers 1% of the Milky Way (which honestly is an unreasonably large number) that is still roughly 2 billion stars and easily millions of star clusters linked in the network.
Thus, the galaxy is quite literally ****** enormous. Mind bogglingly huge. And the relay network is likewise an enormous fraction of an already enormous structure. The likelihood that the region of space which you show on the map was NOT explored at all is vanishingly low - thus, the map is nonsensical.
However, the basic idea is sensible - there are likely vast regions of space that haven't been explore because of previously unactivated relays. These areas of space dont have to be a large area of the galaxy like you suggest - because given that each primary relay can be separated by a radius of thousands of light years, a single inactivated relay could provide a setting for a story that takes place in isolation from the rest of the network but is still massive in scope.
The depiction of the relay network in the Mass Effect trilogy is oversimplified and stunted for the purposes of gameplay and story. Trying to make a meaningful map off of that is likewise an oversimplification.