I actually think killing off Frank Underwood will work for House of Cards (if that's what they do) for two reasons: That's what happened in the original series and Robin Wright's Claire has had such a strong presence in the show from the beginning. Placing in her in the solo lead is the most natural thing the show can do. I just hope they don't try to bring in some male lead to fill in Spacey's gap.
Agreed. That seems to make the most sense and doing so that way would feel organic. However, as for Claire, as strong as she is, the bits where she was on her own didn't quite work as well for me, but maybe that's also because she leaned on him and maybe the dynamics would be different if she were truly on her own. This is not going to be easy for her, given the crap that Frank has done, and it's going to all unravel in front of her and she's going to lose control of the Underwood empire, and I think that's still within how the original dealt with it. Season 5 seemed to be hinting that his opponent had earned a win only to have the carpet pulled from him, so my thinking is that with all of it unraveling that's about to happen, that he'll eventually get what was earned when they need the emergency replacement when that house of cards crumbles away.