Group borrowing and more collaborative living arrangements could become "pathways to home ownership" in future, according to a Commonwealth Bank report.The number of mortgage applications with two or more applicants has increased from 64 per cent to 67 per cent over the past couple of years, indicating that "multi-generational living" is becoming a more permanent arrangement.Other borrowing arrangements might include syndicates and other forms of pooling to buy and develop land.CBA also expects to see more use of guarantees in lending arrangements.Collaborative living arrangements include building smaller dwellings within a development and sharing storage spaces, laundries and other communal areas.The bank estimates that by 2030 new dwellings will be an average size of 119 square metres, which is about half the size of the average house today. Increasingly housing developments will be shared by "communities in common", drawn together by shared values or lifestyle and willing to share more of their space.CBA also sees continuing growth in Airbnb and similar services, allowing home buyers to earn additional income.