Eh, I'll go ahead and admit that my earlier post was a little cynical(had a long day). I'll revise my opinion(s) on the matter.
Mordokai said:
I'm actually with Han on this one. I think Liara would quite gladly drop the SB routine after the war. Sure, she would use her network to do as much good as possible, but after a few years(or hell, a decade, it's not like that's a lot of time for her), I just can't see her hanging on to it anymore. Like you said, the previous two Shadow Brokers met with untimely and violent end and I think this is pretty much the only way to attain the mantle. Liara is smart enough to know that and I believe the prospect of knowing you're living on borrowed time isn't appealing one.
OK, I'll acquiesce to your assertion that Liara would be smart enough to walk away if things did indeed get too hairy(probably in the same "spectacular fashion" when she escaped from TIM's forces on Hagalaz), and she may even give the mantle over to Feron. However, I still don't see her quitting the intelligence trade altogether. I'm also going to stick to my assertion that she won't quit being the SB until the Galaxy(and Thessia) is greatly on it's way to being rebuilt. Again, I can't help but think(and feel) that she will feel a compulsion to help those in need during reconstruction. After that? Well, I guess i could see her moving on to something else, but i still don't see her walking away from the intelligence business completely for the rest of her life.
Also, unlike yourself, I believe she lets it show she really isn't enjoying her new position all that much. There are some lines throughout the third game which let me believe that. Sure, the mysteries of the Protheans may not be that many, thanks to Javik(also, he was kinda ahole, which I think damped her enthusiasm on his people), but she is young... she has upwards nine centuries before her. That's a lot of time and like you said, she is driven. It's a big galaxy out there... lot of interest spheres to explore. She may write a book, she may go into academia... hell, she may learn how to dance the exotic dance for her commander 
I don't really see her hating her position as Shadow Broker in ME3. Rather, I think she hates not having any time to relax. So, I guess I can definitely see her wanting to take some time off after the Reaper War and when everything is almost back to normal. I could also see her 'retiring' of sorts so she and Shepard can settle down for a while(she is only 109, so she's got quite a while to pursue another career after Shepard passes and her children are old enough to live on their own). I don't see her becoming a house wife per se, she'll want to do something that's fulfilling in some way. I can see her becoming a history instructor of sorts at an academy on Thessia, with a focus on archaeology.
Heh, I can also see Javik coming in to help her..."instruct." (Liara: "This manuscript shows Athame teaching our ancestors mathematics." Javik: "Well, as I said before, you couldn't count higher than your toes. We took pity: *Liara gives Javik a steady glare*) After all, they still need to complete their book.