The next Arrowverse show in 2020?

I have been recently going over a few more comic series from the DC Universe lately and I wanted to throw another series I would be keen on seeing. I know with Batwoman coming out, chances on making it happen would be slimmer, but a Gotham City Sirens branch off would be super nifty. Even if they don’t make their own series (I mean imagine the possibilities) the Sirens making guest appearances on Batwoman would be awesome.

I’m really itching for a Suicide Squad series. I would love that. Out of the three you listed, as much as I would love Black Canary, I’d probably go for Green Lantern. Given the the Crisis on Infinite Earths has confirmed Green Lantern will be there, I think this would be the most likely. As much as I would LOVE a Wonder Woman reboot I think my dreams for that would sadly be on hold for much the same reason the Justice League would be hold. The movies. And even though Suicide Squad had a couple of movies, I think the anti-hero group has such huge potential. We’ve already seen with DC Legends and with the Agents of SHEILD that this kind of premise has traction so it would be nice to see it move forward in the future. Not to mention, it would be great fun come cross-over time, the method of “we must do what is right” vs “we must do what gets the job done”. A great contest in approaches I think.

Since Batwoman is my favorite DC character, and I enjoy the Supergirl and Flash series, I am already over-catered for.

Whichever character or team they do will likely be in a different city to that of the current characters. So of the guesses so far, I'd say Green Lantern could be the most likely.

... but a Gotham City Sirens branch off would be super nifty. Even if they don’t make their own series (I mean imagine the possibilities) the Sirens making guest appearances on Batwoman would be awesome.

Well, I would love to see such a series as well!
And I really hope that we might see some of these characters in the Batwoman series as well at some point.
I guess not in season 1...but they should include some well-known and popular characters like these later on.

Not really fresh news anymore, but since I started this topic, here is the answer:

It will be:
„Blackstar“ aka „Star City 2040“ with the sons and daughters from team Arrow,

https://ew.com/tv/2019/09/24/arrow-female-centric-backdoor-pilot/
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So far, it's "just" the pilot which is ordered.
What I am wondering about:
Will it be like in Arrow, so that the two "older" canaries are already near 50 years old?
Personally this setting would be a little ....odd....for a whole series. A 20 year old with her two 50 year old canary sisters as back-up? And two around 30 years olds would play older versions of themselves the whole time, during a whole TV show?
Hmh...