If you really have to have a particular person and nobody else in the world could possibly do, then you have that conversation with the cleaner surely? You let them know that the job is there for them as soon as lockdown ends. You can be honest about your own financial circumstances and how much uncertainty exists for you if you feel the need to share. They can tell you what’s going on for them. Then you could make an arrangement, I guess. But nobody is obliged to do this.
But I think in the vast majority of cases, people don’t know how long lockdown will be going on for; they don’t know what the hell is going on with their own jobs or what financial position they will be in after all this. So “will the cleaner ever return?” is probably the least if their worries, frankly.
I think the people who are more dependent on their cleaners probably have ones who they maybe push the boundaries with tbh - eg “oh you don’t mind watching the kids while I pop out for 5 mins, do you?” So the cleaner is more multi-tasking in a way, perhaps more like a housekeeper who feels more part of the fabric of your family, perhaps? For other people, the cleaner comes - hoovers, mops, dusts and a quick wipe of kitchens and bathrooms - and there’s no more to the relationship than that. It’s a job, take it or leave it. Same as the carpet shampooer, just with a vacuum instead.
I guess for some elderly people who might be on their own, they might become more dependent on their cleaner as someone to chat to regularly. On the other hand, someone who works might literally never clap eyes on their cleaner. It totally depends on what kind of relationship you’re paying for, I guess.