EOAProxy.sol

pragma solidity ^0.7.0;

contract EOAProxy {
    address implementation = DEFAULT_IMPL_ADDR;
    function _eoaUpgrade(address _newImplementation) external {
        require(msg.sender == address(this));
        implementation = _newImplementation;
    }
    fallback() external {
        address impl = implementation;
        assembly {
            pop(delegatecall(gas(), impl, 0, 0, 0, calldatasize()))
        }
    }
}

Example upgrade

import EOAProxy
contract Impl {
  function upgradeImpl(address newAddr) {
    EOAProxy(address(this))._eoaUpgrade(newAddr);
  }
}