I doubt it would work.
Perhaps a spinoff centred round Sara Lance might have worked 3-2 years ago but now she's on Legends it wouldn't work anymore.
Why wouldn't it work now? I am curious? What's preventing this from happening? No writers? No directors?
If they do a spin-off, I hope its called Birds of Prey (no, not that 2002 series one). Today, there's too many male action solo/team-up superhero show now. We need things to balance it out a little bit. There's Supergirl, but that's about it.
My ideal team would be:
Black Canary
White Canary
Huntress
Katana
Barbara Gordon (Oracle)??
Lady Blackhawk?? (Maybe as a transportation driver?)
That's it. Don't want too many, otherwise I think it would require a huge budget. And have it set in a different city, maybe Platinum Flats, CA? Also keep Marc Guggenheim off this show, the last thing we need for him to come in and destroy it all over again. Probably get Gail Simone involved in this project too.
If they plan on being in the same universe as all the other CW shows, then I guess, they will have to bring back the original cast (Katie Cassidy, Caity Lotz, etc) to reprise their roles. But if it is indeed separate, then I wouldn't mind a new actress casting in it.