The interesting part of Mobike is the points system for users, as described in Helen Pidd's first Guardian article linked upthread. A user is given 100 points when they register. Users lose points for parking badly or leaving a mobike where it can't be hired. But they earn points for reporting bad parking, and for using Mobike bikes. More about the points
here. In this way, the company has gamified user behaviour. In part, this is how they manage not having Boris-Bike-type docking stations.
I think Mobike now need to develop the game, to resolve the problems that Helen recently documented (such as people keeping Mobikes for themselves in their own front yards). Easiest part of this would be increasing the points awarded for being helpful and points docked for being unhelpful. They could also consider making points spendable outside their system. I'm not sure if points can be cashed in currently, or even whether they can be spent on Mobike hire. That's the sort of nudge that could keep the scheme functional. They've got to do something like this because, as far as I can see, that's the only handle that Mobike has on user behaviour.
Another rule might be a requirement to upload a snapshot of the bike after you've parked it. In some cases, it would be clear from that photo, in combination with the GPS data, whether the bike is on private proprty. That wouldn't be onerous, because the system requires users to have a smartphone already.
In addition to changing the game in these ways, I think Mobike could consider offering a parallel hire scheme so that users who want sole use of a bike can rent something for a defined period. That could work along the lines of Brompton dock, or indeed car hire. Those bikes wouldn't appear on the map for 'pay per ride' customers.