Mixin to apply over the Django `User` or `AbstractUser` model, this will change the superuser checkbox to a datetime field that will expire.

expiring_superuser.py

from datetime import timedelta

from django.db import models
from django.utils.timezone import now


class ExpiringSuperuserMixin:
    _is_superuser = models.DateTimeField(
        _('superuser until'),
        blank=True,
        null=True,
        default=None,
        help_text=_('Until when the user has special top-level permissions. Use with extra caution, '
                    'this includes most destructive permissions. Only specify a very limited timeframe.'),
    )

    def save(self, *args, **kwargs):
        """Clear superuser field if expired.
        """
        try:
            if self._is_superuser < now():
                self._is_superuser = None
        except TypeError:
            pass

        return super().save(*args, **kwargs)

    @property
    def is_superuser(self):
        """Evaluate if superuser datetime is not due or None.

        If the datetime is due then reset the field to None.
        """
        try:
            is_within_window = self._is_superuser > now()
        except TypeError:
            return False
        else:
            if not is_within_window:
                self._is_superuser = None
                self.save(update_fields=['_is_superuser'])
                return False
            return True

    @is_superuser.setter
    def is_superuser(self, value):
        """Backwards compatibility: set a default time for superuser.
        
        When using `manage.py createsuperuser`, this method will be called with `value=True`.
        In that case we need to set a default time starting now.
        """
        if isinstance(value, datetime):
            self._is_superuser = value
        elif value is True:
            self._is_superuser = now() + timedelta(minutes=30)
        else:
            self._is_superuser = None
    
    class Meta(AbstractUser.Meta):
        permissions = [('can_assign_superuser', 'Can assign superuser')]  # Creates permission on model creation

user_admin.py

from django.contrib.auth.admin import UserAdmin as AuthUserAdmin


class UserAdmin(AuthUserAdmin):
    fieldsets = (
        (None, {"fields": ("username", "password")}),
        (_("Personal info"), {"fields": ("first_name", "last_name", "email")}),
        (
            _("Permissions"),
            {
                "fields": (
                    "is_active",
                    "is_staff",
                    "_is_superuser",  # <--
                    "groups",
                    "user_permissions",
                ),
            },
        ),
        (_("Important dates"), {"fields": ("last_login", "date_joined")}),
    )
    list_filter = ("is_staff", "_is_superuser", "is_active", "groups")
    
    def get_readonly_fields(self, request, obj=None):
        """Only allow editing superuser status when has can_assign_superuser perm.

        The has_perm() check also triggers is_superuser() to reset it if needed.
        """
        readonly_fields = super().get_readonly_fields(request, obj)
        if not request.user.has_perm('profiles.can_assign_superuser'):
            readonly_fields += ('_is_superuser',)
        return readonly_fields