Snorty Pants, could I ask you (totally respectfully), what is wrong with recommending euthanasia? Life happens and a horse owner does not have the time or money to care for their horse (many of us have been there), and does not have friends or other contacts who would be able to step in and offer a known-to-be safe landing. We all know the risks of sending a horse to a retirement situation that is too far away for the owner to keep eyes on. On the other hand, maybe the owner is in a position, at least legally and logistically, to euthanize and therefore see that the horses never end up starving, stressed, physically abused, or on a meat truck to suffer the trauma of that end.
The OP did ask a bunch of strangers about retirement options, you are right. Euthanasia might be one realistic retirement option, based on the experiences of this “bunch of strangers” who collectively have loved a lot of horses, seen a lot, and thought things through alot. Sometimes, euthanasia is doing the right thing by the horse.
No one is judging the OP; we are all just offering information. The OP can do with it what they want.