We have cooperatives in a lot of forms being part of our existing system. This is in the form of housing coops, cooperative banks, cooperative stores and worker owned companies. All of them survive and some even thrive in our current system. Mostly they are growing slowly, if at all, but are much more stable and fiscally conservative. They can even work very well on natural monopolies as utility cooperatives have shown.
There are also legal setups like trusts, which can be very benefitial, if done right.