The "crossover" execution environment aka Eth1-esque abstraction over Phase2
The current proposals for Eth 2 Phase 2 revolve around a purely stateless architecture, where the only stored information is the state root of each "execution environment" on a shard. This is in stark contrast to the stateful mode of operation on Eth1.
This model expects higher level abstractions to be built atop this simple system. Here follows one proposal to achieve a familiar environment as a higher level abstraction.