Its a worrying thought though I get the idea behind it I am really worried about it and also about places being put into lockdown and going out being restricted. My mum is 72 and has alzheimers and I visit every day to give her her tablets and make her dinner and mainly to keep her company and check she is doing ok and not doing something shouldn't. She could stay at home but I would still need to visit her very day and do her shopping, pay her bills, go to chemist etc for her, which I do now, sometimes with mum sometimes without. Its no problem going without her but I don't drive and go over every morning on 2 buses then at evening hubby comes after work and has dinner and we go home in car. So even though she'd be isolated we wouldn't be and so could still be taking germ in to her. Which I do worry about now but don't have an alternative.
My inlaws are both over 70 though in good health, they get there money out of post office, shop a bit most days by bus in next village or town or locally, pay all their bills locally, they do not have internet or proper bank cards so can't do online shopping or online bill payment. Hubby or his sister could order online shopping for them and I suppose they could call and give details of bills over phone for us to pay online and pay us back later and they do tend to keep a well stocked pantry so could probably manage for a while on whats in there already, they have each other for company so they could possibly manage a little better than mum though I think it would still be a struggle, especially mentally as they like to get out for a little while most days.
If staff are ill or fear for their safety from coming into contact with infected people online shopping for delivery could be suspended or we could just not be able to get delivery slot due to high demand. If lots of people get ill then goods won't be being made, or delivered, or shops might not have staff to work so eventually things could get really difficult. I think its more the effects of what we do to prevent virus has on daily life that I'm worried about than the virus itself at the moment.