There's been a number of posts on this subject. If they have no money and suffer infirmities, they are offloaded, either to their families, if they are lucky enough to have a family willing to care for them, or to facilities funded by the State. Since they have never accrued enough quarters for SS or earned an IRA, they will only qualify for SSI and Medicaid. Any indigent person 65 or over can qualify for SSI/Med. The cult probably knows about this safety net which would make the dumping process easier.

However I feel in my bones that all too many Scientologists never make it to 70 or beyond because their life expectancy is lower than the average. I think it is now around 75 for men and close to 80 for women. This is due to the harsh working environment, poor nutrition, lack of sleep, stress, and notably failure to seek medical intervention when symptoms appear.
I think the cult would be wise not to challenge this opinion as they would be hard put to disprove it.

Senior scientologists who have given everything they had to the cult and are now too old or ill to be of use to the cult and can't even afford the care they need because the cult didn't pay their Social Security and took all their money are still expected to put in "exchange" when they are old and sick. Most elderly people don't want to be a burden to anyone, and this attitude just rubs it in. It goes hand in hand with the stories of EOC...when you are no longer useful you should drop your body.