The so-called Drivechain protocol is an extension to main Bitcion network. It can be forked into the base Bitcoin operations, adding new features, e.g. sidechains to enable faster transactions, smart contracts, faster block processing. And while new features are added, it's not an altcoin, but a tethered add-on to main protocol, working side-by-side with mainstream blockchain.
Drivechain had a very shaky foundation because all of the previous variants were considered a pipe dream, but right now everyone can get a look at the existing code, courtesy of Paul Sztorc. He has a reputation as a developer of Bloq, enterprise-grade blockchain technology, and Hivemind chief scientist.
Now Sztorc proposed a set code for implementation of sidechains augmenting existing blockchain network and currently asks for code review from his peers. One of the current Bitcoin Improvement Proposals (BIP) focuses on the hashrate escrow concept, which essentially is a variation of multisignature escrow, signed by the third-party miners not by a private key but by dedicating their hashpower to the transaction. Second BIP revolves around Blind Merged Mining. According to Github proposal, it allows for 'extension blocks' to be used in two or more sidechains for mining without any need for validation, it produces strong guarantees that the block is valid according to any set rules because of the multichaining.
As of now, two new BIP are awaiting formal numbers from developer community. Many people believe that the sidechain technology can be beneficial and will remove the need for many altcoins employed today by providing the same features in mainstream Bitcoin network.