Actually, I really like where they've taken Liara's character because it gives her the potential for a whole lot of depth. I don't buy the anger or her strongarming people, but the idea of her being good at disseminating information and having to deal with horrible guilt for 2 years is very compelling.
The implementation was absolutely horrible though and they don't do anything with the potential. It's a real shame, since they could make her the character with the most complex relationship to Shepard. They didn't put in the necessary detail to do so, though.
As for DLC, I think it will feel extremely false if Shepard and Liara can't talk about their relationship. Even if she's not the LI, she must feel something very close to love or adoration in order to attempt to recover the body.
Ideally, they'd handle the actual mission similar to Jack's loyalty - where she comments on everything and you can ask for more detail on specific items and video logs. The player needs all the blanks filled in, because they likely have no read the comic. Then, afterward, the two really need a long discussion to talk about what happens next (whether they are lovers or not). If she's the love interest, it's totally unbelievable that this would not include a discussion about the two of them. Not including it is being willfully obtuse and doesn't make any sense at all.
I don't think it makes sense for her to stay on Illium and analyze data though. Maybe if she's really paranoid about Cerberus - but that seems like a lame cop-out to make sure she's not a squaddie more than anything else.