Marcone won’t hand over the castle, but if he ends up owing Harry a favour in BG, or Mab purchases it for him then yes, Harry could end up owning it. A castle abode of the Winter Knight would help forge a connection in the Never Never to Arctis Tor, and perhaps allow Harry to forge one through the Never Never to the cottage on Demonreach, much nicer than Lea’s Murder Garden. Lea may have a green thumb, but the rest of her hands are red right up to the elbow.
Commute? To a different time zone for the single parent of a school age child? Much easier to have someone like Chandler do a daily courier run with relevant reports.
Luccio still has all her experience and knowledge, so a senior Council position is still likely.
Harry is The Warden, the Senior Council cannot take that away from him and everyone will know (Lara, Listens and Eb know at the moment), their options are have to Harry in the tent p@ssing out, or outside the tent p@ssing in. If the main surviving body of Wardens look to Harry rather than the Merlin, then Harry gets to dictate terms like he did on becoming a Warden.
His terms I think would be along the lines
1. Continues to work out of Chicago;
2. Warlocks are rehabilitated or get the Demonreach Treatment, no executions;
3.Amnesty for all Wizard level talents who have not broken the laws (Mort and Elaine);
4. He continues to work as Winter Knight on behalf of all the Accorded Nations;
5. Better treatment and recognition of the Paranetters;
6. Gets to put up a Basketball goal in his new HQ