Bethesda has confirmed a few details about how Starfield player homes will work in a new fan Q&A. In short, you'll be able to purchase someplace to live in all major Starfield cities, and other options will be available if you complete certain questlines.
In a Q&A hosted on the official Bethesda Game Studios Discord, lead quest designer Will Shen explained that "there’s housing in different cities that the player can get. Some you have to purchase and some are rewards for specific quests."
Lead designer Emil Pagliarulo added that "you can purchase a dwelling in all the major cities in the game. And there’s at least one that you get specifically for completing... something."
Details on whatever that mysterious "something" is will have to wait, but it's good to hear there'll be at least one secret hideout to unlock. Previously revealed Starfield traits include one that would give you a 'dream home' with a major loan to pay off, so we already knew player housing would be in the game in some form, but this is our first concrete information about how the system works.
Bethesda has made a point of including purchasable player homes in its (relatively) recent games like Skyrim and Fallout 4. Skyrim offered some basic housing options at launch that were dramatically expanded with the Hearthfire DLC. Fallout 4 included similar options, but also included much more robust systems to build entire settlements - and it seems the Starfield outpost system will offer similar options here.