Do you think they'll still screen what they managed to shoot of Series 5?
Probably; I hadn't seen Series 4 so I don't know if it ended on a cliffhanger, but SJA stories tend to be stand-alones so if they managed to complete a couple of storylines I can't see why they wouldn't air them.
All that said, I saw one blog suggest no Series 5 episodes were made because of her illness, but that's not what I recall reading in the filming reports. We'll hear fairly soon. If they didn't end up filming any Series 5 episodes after all, the title of the Series 4 finale will be even more poignant.