At least we'd likely know immediately when it happens with the other two. With Lucas, we'd have no idea and just assume he's dead after extended inactivity.
His parents have to be notified by law so its likely his mother will go on her usual self absorbed lucas tier
oh my poor baby lucas! everyone was out to get you! you're a victim of all these evil people and the system who hate the mentally ill! bs she usually puts on when he comes up. Not for his sake, but for pity points from her circle and anyone stupid enough to believe her. Never mind that she abandoned him nearly 20 years ago, wants nothing to do with him herself, knows exactly what he is (and even lucas admits this but doesn't appear to have the self awareness to realize it, hence the 'its not in the cards' stuff) and would probably lose her shit if he suddenly turned up at her front door
In other words, his mother will make it known pretty quickly after he dies, so if there is a sudden absence of the wern its probably best to keep an eye on her posts for awhile
That said, doctors always point out the ways to deal with issues like his - changes in diet, dialysis, etc.. so it'll be interesting if he never mentions why hes not going to be getting a new kidney when it becomes too obvious to lie about anymore. I mean for obvious reasons he's never going to get one from the normal get put on a waiting list method, as he'd never qualify for it and even if he did somehow get one that way he'd never adhere to the required diet afterwards and the medication and he'd either destroy the new kidney or fuck up his meds and cause it to get rejected, but he'd definitely be informed of the possibilities of a donor from his own family. It'll say alot if he never mentions this, as its overall his only chance and best hope for a compatible match. No way he wouldn't feel entitled to a kidney from his family, especially given their lack of providing for him in other ways, so it'll strongly imply he made a demand and was refused by all of them, which will show what they really think of him and why he wouldn't bring it up
The only way I could see any of them giving him a kidney is if they did it in exchange for power of attorney over him and guardianship so they could lock him up in some nuthouse or whatever for the rest of his life to keep him out of their hair and away from the public. Which of course, he would spaz out about and refuse. Though I wouldn't put it past him entirely to beg for one online like he begs for door dash. and frankly if he does he deserves to get door dashed a bunch of raw cow kidneys from the local supermarket on principle for being that greedy and entitled
Perhaps he'll get lucky and it'll turn out there is some kind of afterlife. on the other hand if there is maybe he'll end up as the new roommate for john s bulla (sexually, of fucks) and have to put up with him, his magazines and knife rope necklaces for eternity. I'm not sure I want to imagine the kinds of toasterbortion foods those two would spend eternity coming up with. Then again maybe john will get it in his head lucas was really the guy posing as his pedo demon clone he met at pizza hut and spend eternity guarding his side of their celestial shithole apartment with his knife necklace to keep lucas away instead