If you're using the MultiChain protocol, i.e. with support for permissioning, native assets and streams, then MultiChain is the only compatible software that can act as a full validating node and miner. However, since the MultiChain protocol itself is very close to bitcoin's, any bitcoin-compatible wallet can be easily adapted to work with MultiChain.
The source code for MultiChain is now available, so this should not be too much of a concern. In the unlikely event that we stop developing the platform, anybody is free to fork it and continue the development.