Having a heart attack and potentially dying. What if, perhaps, he is being killed off because Michael French requested a break, or to leave and come back in a few months, and DTC has decided to kill him off because of that? Sounds harsh, but if David is killed off, it would send a very strong message to the rest of the cast that Eastenders is somewhere you should be committed to, and not a revolving door for you to come and go as you please.