I said I'd keep you posted when my cat dies, but it seems it won't be for now.
 Yesterday, the night was fresh and he ate quite a bit. I mixed some of his
blended gelatin + tuna mix with regular cat food and he ate everything.
Almost, at first. Of course, he managed to leave some cat food so that I'd add
more of his favorite gelatin mix. That's what I call having a picky tongue:
the gelatin and cat food were quite well mixed.

I also fed him some ham. I suppose I shouldn't, but it's well cooked and he
likes it. Anything he like goes, these days!

I'll also give him about 1/6 human multivitamin pill a day until he resumes
eating dry food... that is if he ever does. He really seem to appreciate
playing "fine gueule". I also give him about 125 mg of glucosamin/day because
he seems to have bone/arthritis problem, but I believe the temperature drop
has more to do with his recovery than these supplements.

So, to all the vet senders, yes, at more than 17 y/o, my cat is bound to die,
but not today. Cats are pretty good little vets themselves. When mine felt a
heat wave was coming, he knew his old heart would have a hard time gettimg him
through. So he went on a diet, shedding every single gram of fat in his body.
I wished humans could do the same. The heat wave certainly has been harder on
me than on him...

Comes September, he'll put on some weight.