Developing retrofit cohousing is indeed fraught with problems that tend to differ from conventional cohousing. And the resulting form is likely to be suboptimal. However tho your examples are possible, they may not.
Common facilities are possible tho maybe different.
I am aware of two retrofit cohousing communities who have folded in the last year or two. Clearly retrofit develpoment does have problems. In both cases, bad feelings and differences of opinions seem to have made folks reluctant to discuss the details. Too bad, it would be nice to learn from our failures.