Pro 3. A Lot of Good Stories can be Written for Her...
What makes Angela so fascinating is that she's a hero who fights the good fight...but tends to see the world in black and white. Marvel is a very gray universe, so there is the potential for a lot of "misunderstandings" can occur, which would result in conflict. Stories need conflict. Marvel can show her character undergoing a gradual change over time, going from rigid and militaristic to softer, understanding, and noble, much like in the original Spawn comic. However...
Con 3. ...They Killed Her Off for a Reason
The reason they killed Angela off is because they felt she could no longer contribute to her universe. Despite being a popular character, they didn't know what to do with her. Now, by throwing her into the greater Marvel Universe, maybe writers have a new idea on how to use her, but there's always the possibility that they might just run into the same problem MacFarlane had...