I think the prices for bike sharing are absolutely unsustainable and so I'm not surprised about the collapse of the market for rental bikes. A bike that is kept outdoors needs 0.5h per week of maintenance and I don't see that possible at current prices and with bikes not being in a central location.

I used to keep my bike outside and it went a couple of years with no maintenance to speak of. Maybe some tyre pumping. As long as the bikes are not vandalised / stolen / chucked in canals etc I think the economics could work.

In what climate? Having lived in UK, Germany and the US East Coast with rain and snow, it would not have worked for me and bikes that are used a lot by people who are not careful.