ETA: I feel I should comment on the idea of Alex Danvers being gay. I don't have a problem with it, but it feels the easy way out. For Maggie Sawyer, it fits the story they set up. She's a double minority being a person of color and gay (triple if you count that she's a female cop). That causes her to identify with the alien community. Alex doesn't have that, which is fine, but obviously isn't as interesting. On top of that, I like the idea that a straight woman can have respect and admiration for a gay woman without it being "she's secretly in love with her." I feel it would force themselves in a box and limit their message by doing that. I also don't think they should go down the route of all badass females who aren't overly girly must be gay. I think they add more to the discussion of sexual orientation by not going down that path than if they do.

You know, I think it is a myth, a pretty popular myth at that, that TV shows all "badass" women who are not overly girly (by which I assume you mean people who do action scenes and roles that are traditionally identified as "manly") as lesbians.
Granted that I have not seen all the TV shows in the world, but other than the POI characters (and one is slightly girl in that), I cannot list any from off the top of my head that are lesbian or bi.
That is two (plus two in 100, if the rumours are right, but am not sure if they are girly or not since I have never watched that show).
On the other hand, I can list many that are cops or detectives, have actions scenes and are straight.
- Beckett in Castle
- Olivia Bensen in L&O SVU
- Amanda in L&O SVU
- Carter in POI
- Carrie in Unforgettable
- Jackie in Blue Bloods
- All the other rotating detectives (3 at least) in Blue Bloods
- Jane Rizzoli in Rizzoli & Isles
- People on NCIS, Mentalist, and so on...
And there are many others that I am not remembering or have not watched. After all, there are cop shows and action shows out there with women in it who have action scenes and investigate and so on and still are straight.
If by girly, you mean people who wear dresses or makeup, Alex does both when the occasion demands it; as does the people in Person of Interest. And many of these above detectives and action folks.
Can you have more varied and diverse LGBT and ally representation in TV? Yes. Is it desirable? Also, yes. But, does it happen? No. Even some representation is considered a lot or too much by many. And a lot of it is concentrated in one or two shows.
Note: I really don't want romantic storylines on either side to take away from the Danvers' story line or time, but that is a completely different discussion.
To add to that:
One of the ways in which relationships grow and are tested is when one or both siblings enter into other relationships and we find out how that affects the central relationship.
So, I am interested in that dynamic and finding out how they react to it and deal with it and finally come out stronger at the other side; because they have to come out stronger.
We have seen how Alex reacts to Kara spending all her time with Clark, now let us see how Kara reacts to Alex spending less time with her and more with new friends.
Also, even if Alex and Maggie just become friends, that would be something for Alex because Alex needs friends and game nights, just like Kara.