I like the concept. But I think there are certain issues to consider from my
experience with a
greenhouse and black raspberry. I am using the rasberries as a seasonal cover. I have a grape to help, but it's too small yet to affect the plastic. The plastic I used was from the hardware store, not specialty
greenhouse stuff, though I hear the greenhouse stuff doesn't last either. This structure also has roll-up sides to save on plastic and allow circulation.
Now I have told you of where I'm coming from, here's what I noted:
1: plants grow. Obvious, but plastic doesn't. Also obvious, but you see where this can get a little awkward. Not only do plants grow taller and wider, they grow more branches and those can sometimes scratch and penetrate surfaces they are next to. If you leave
enough space for the plastic to grow with the plants, it can also flap in the wind, banging against sticks, and tearing.
2: greenhouse plastic is made to be attached with wiggle wire or another multipoint attachment thing. Plants, however, get sick with some unbreathable surface attached to them so thoroughly...or maybe
root growth can occur. If you attach it less, you end up with points of failure, flapping, and tearing because that plastic is weak.
3: depending on where you live, you may need to consider
water or snow load + the strength of the
trees. With a fixed structure you can shape it so most snow slides off, but if there's sag, snow will likely catch and then, you can either damage the structure or look forward to removing the snow regularly.
Good luck!