Long-time maintenance or any other sort of service contracts are almost impossible in the ACT. They are generally limited to 3 years. From memory I think they can be a perhaps two years longer for the first five years of a new OC but nothing like 99 years.
Also, I think an embedded network is something quite different and there are strong consumer protections around them already. The embedded network I am aware of is where the OC negotiates a better price for an energy supply, usually electricity, on behalf of the owners. Rather than each unit paying a separate account with a retailer, the OC has an electricity meter for the whole site and pays for that one supply. Then the individual owners pay the OC pro rata for their consumption. This requires the OC to read meters but it might be able to that at lower cost than the retailer and multiples of supply charges are avoided. If the OC has a solar electric system behind its meter, the common property of the building and all the lot owners are likely to consume the entire solar production, thereby avoiding the retail price of electricity to the extent the building generates its own. The benefit is shared by all the owners since they collectively only have to pay for their share of the import by the building and the common property electricity costs are lower too.
The Australian Energy Regulator has strict requirements that enable people to opt out of such embedded networks if they feel they can get a better deal by signing up with a conventional retailer.