A collection of active areas of research related to staking
Adjusting the issuance curve has been a topic of discussion primarily aimed at addressing increasing validator set centralization. A comprehensive resource maintained by Caspar can be found at issuance.wtf.
maxEB raises the amount of ETH that a validator can hold from 32 ETH to 2048 ETH. It is slated to go live with the Pectra hard fork.
Inclusion lists are a set of proposals aimed at increasing censorship resistance of the network in light of increased censorship caused by external builder centralization.
mevburn aims to address centralization caused by the volatility in MEV rewards and increase the cost of censorship at the builder level.
Enshrined Proposal Builder Separation removes the necessity for relays by allowing validators and builders to interact trustlessly.
There are a number of proposals in flux to adjust the structure of block building on Ethereum. Some of these separate the parties who attest and propose (as proposing and building is mostly separate today). Some break up who has the rights to build pieces of a block. Some change how proposers are chosen. All of these proposals seek to address increasingly unsustainable centralization that has emerged from the current structure. This area of research is the most active and broad on this list.