Has there been any signs of Quarians so far?

Can they leave permanently the Migrant Fleet permanently, taking with them a sizable population and never return, just like that?
As far I know based on general in-game lore, each and every Quarian individual is committed to the Fleet, and one only leaves (with the promise of coming back) during the Pilgrimage. I believe this is the understanding that most people who have played the trilogy have.

But since I have never read the books, I am unaware of what subjects within ME universe they deal with.

So you're telling me that I'm wrong because the fans would be angry at the endings and possibly choosing one as canon to continue the franchise  in the milky way. Is that not just an extension of the anger the fans had anyway about the original endings? I'm not saying the writers are blameless. They did write themselves into a corner, but the fan base overreacted so negatively that they had to change the setting.

Its not really playing devils advocate or making an assumption to say thats the reason they changed the setting. That was the reason they changed the setting. The developers have basically stated this a long time ago. 

The trilogy finished 5 years ago, does it really matter if they chose a canon ending now and learned from their mistakes for future games? I personally don't care too much about that myself because everyone played all three endings. We all need to move on. 
And if push came to shove, you could have had the next mass effect game so far into the future that eventually all three endings would merge. Mass effect are great at creating the illusion of choice in video games. For example, it didn't matter if you destroyed the collectors base or not in ME2. The IM was still using reaper tech in ME3. 

1. The reapers were destroyed but the relays were repaired. Life continues and maybe some geth that were offline (maybe the heretics) escapted the destruction of artificial life or (insert technobabble here), not all quarian ships choose to join the fleet in engaging the geth, the krogan still  had the genophage and they wouldnt be wiped out because of that. Thr genophage maintains a low population, it does not make the krogan go extinct. We don;t know anything about the hanar or drell (actually the drell were gonig to go exitnct no matter what) and some batarians didn't live in batarian space, such as the ones we see on the citadel in ME3. 

2. Shepard takes control of the reapers and they rebuild the mass relay network and the rest of the galaxy. But eventually the reapers are dismantled because they are no longer needed and the shepard AI went offline once galactic peace was reestablished. You can dress it up, I can't really go into it in a few lines on this post.
3. Artifical and organic life merge and they understand each other completely. If you put the story far enough into the future, this will happen anyway. That ending was so vague as to what the merging of artificial and organic life meant that we don't really know what that means to the ME galaxy. 

I mean don't expect me to go into massive details to address every single item of minutia in this post about how they could have continued the game after the ME3 endings. Its not impossible. 

If you go 1,000 or 2,000 years into the future anything can happen. Look whats happened in the last 2000 years of our own civilisation. Were roman philosophers writing about how one day man would walk on the moon and establish colonies on mars and fly faster then sound?

But the idea of starting the franchise in an entirely new galaxy was to escape the endings because of the fan reaction. And now thats what we got. A galaxy without quarians. A franchise possibly without quarians? If thats true, then they might as well be extinct because fans will not see them again.

I think you missed the point, since you spent 95% of your response addressing things we actually agree on. I've never seen them specifically address it, so could you please link to where any of the devs have said fan reaction to the endings was the definitive reason they changed settings? Unless you are one of the developers or process clairvoyance, such a declarative statement is usually backed up by evidence. Otherwise, it is by definition an assumption.

It makes much more sense logically that the reason they would be forced drastically change settings is because they wrote themselves into a corner making it virtually impossible to continue the current storyline. Regardless of fan reaction to the original endings, this would have been necessary because of the way they chose to write ME3. You may not care what happened in your storyline, but in my observations, the majority of the fanbase does, deeply so. Could they have continued it the way you described? Yes. Could they have continued it without invalidating the indivifual stories of a vast majority of their fanbase? No.

They picked what was likely the best of their limited options. This leaves everyone's individual stories intact while continuing the franchise down a tangent path that is unaffected by anything that came afterward. Did the response to the endings make this decision more likely than the alternates? Probably. But even without it, this was likely the path the series would have gone anyways.

They would have the same problem as turians, finding a dextro dna livable planet among Heleus's few choices(which seem to be dwindling down), and how much rations does the Ai really have for these species, if a suitable planet is not found, I ask?

Ofc if they find the planet, they could live there among turians, unless theres a huge star radiation or something thats tolerable to the turians but not quarian, unless they wanna continue to live in those suits.

Oh yeah forgot about that farming.

Considering their immune systems they will still have hard time getting to live on any planet they find thats not Rannoch without those suits, maybe centuries.

Also considering populations, im pretty sure AI has prepared something like artificial means, embryos and such, and growing them in tanks, so its just not going to be normal baby making.

Be aware of one fact, you could theoretically meet every other species from milky way. Who said, only the Andromeda Initiative got people there. Maybe we will also meet a Prophean colony. ;-)

The newest briefing mentions one of the Golden Worlds being Detro-Amino for Turian and Quarian colonists.

So expect to see Quarians on that planet.

Confirmed! WHOO HOO!

I might be a bit cautious on this confirmation....we did see one Ark going down in flames in one screen shot did we not?

Was it?  I didn't know if we ever got info on which one it was and who was on it.

Yeah I'm a bit confused myself. I remember hearing it was the Asari that went down, but I'm not sure anymore.