Good lord... the junimo hut is gigantic compared to the interior of the greenhouse. I wouldn't want one in there because it would take up too much space and I couldn't grow as much ancient fruit in there.
What's to stop it being able to be built on the "fruit tree ring", thus not taking up any Sprinkler-able crop space?
I don't think a system whereby (once setup) you can gain crops
without doing a single thing has a place in Stardew; at that point you can AFK farm income, all you have to do is sell the crops.
To a certain extent, this is already possible with Auto Grabbers, Auto Petters, Auto Feeders and Silos, but it requires
significantly more effort to get equal reward, and so the Effort In vs. Reward Out is more balanced IMO.
I also think that not being able to have auto-harvesting is part of the trade-off of using the Greenhouse/
Ginger Island; you can't have everything (because you already only need to plant once).
So if this was going to be implemented, to make it more balanced, maybe the Junimo Hut (when in the Greenhouse) could only hold 1 or 2 stacks of items (rather than the full 36), and would act like a Fish Pond, and so you wouldn't get any starred crops?
I feel that this idea needs limits, otherwise all other forms of money-making will become even more insignificant than they currently are.