I know that the idea of new strongholds could be a long shot and might not happen, but if the Devs decide to read this thread we can give them a couple of ideas for future strongholds.
Strongholds for Korriban and Tython- A new stronghold for each faction and could be another option to replace Dromund Kaas or the Coruscant stronghold.
A Stronghold on Alderaan- This could be another shared stronghold that's main feature is a large outdoor courtyard. It also could be built on top of a mountain to provide a view of both House Organa and House Thul.
These are just ideas that I think are cool. Be sure to leave feedback or other suggestions for Strongholds.