Things have changed somewhat in the last few days -- he's been into hospital and they've pumped him full of antibiotics (to beat down a lung infection he didn't know he had) and extra steroids (a treatment he's already on for emphysema), and the improvement since then is remarkable.
So it's now no longer any more likely than usual that he'll die in the next week or two, we're back once again to the "sometime in the next few months" that we've been working with for the last year and a half.
Of course he has some of the side-effects you'd expect from using substances like these in quantities like these, but they're making a real difference to how easy he's finding it to breathe.
Thank you all for your good thoughts and kind words over the last few days.
In other news, I've been occupying myself productively by wiping and re-installing a laptop he's received from his son, full of viruses and other nasties.