This would really help with the issue we have with wolves, foxes, and other small to medium "denning" animals need huge caves or shelters that are so much larger than their real life burrows would be. I have to put some of the smaller animals in such huge habitats, just so they will have enough shelter that doesn't take up half the space. They look so teeny in those.
Another thing that would be cool is if you could set up the burrows with a one-way glass panel on one side, so guests can look in from a darkened room without disturbing the animals. The TV screen system is broken right now, with the flickering issue, and I've seen real zoos that let visitors look into burrows in "real" time.
Re the beavers, it would be fun if they could make their own lodges within their habitats from materials provided.