We’re reluctant to talk too much in terms of a technical roadmap because this is software: things can change. We think it’s easier to understand what’s happening when you read about the outcomes. View the upgrades
But if you’ve followed the discussions, here’s how the upgrades fit into technical roadmaps, and a bit on how they’re changing.
Phase 0 described the work to get the Beacon Chain live.
Phase 1 originally focused on implementing the shard chains, but prioritization has shifted to “the merge”.
Phase 1.5 was originally planned to follow shard implementations, when mainnet would be added as the last shard to the Beacon Chain. To expedite the transition away from proof-of-work mining, mainnet will instead represent the first shard to connect with the Beacon Chain. This is now known as “the merge” and will be a significant step towards a greener Ethereum. More on proof of stake
Though the plans around Phase 2 have been a point of intense research and discussion, with the merge planned before shard chains, this will allow for continued reassessment as to the needs of Ethereum development moving forward. Given a rollup-centric roadmap, the immediate necessity of shard chains is debatable. More on a rollup-centric roadmap