I made the calculation of "forever" via internet-time-units. It was longer than a year. According to Wikipedia, it was... 2004.
But seriously, you're right that the challenge is in actually designing a good UX for yourself. You've got four months to mimic Reader if that's what you want to do. I'd suggest XSLT, since RSS actually predates JSON, it's so old. That doesn't allow for any potential mistakes by RSS creators, though, which might be hairy. /shrug
And not every browser has implemented them. Do you have control of the when they are updated, and how often etc? I like the idea though of perhaps just having them as simple bookmarks. That would allow for easy syncing.
Syncing history - could help regarding your reading history (privacy aside.)
Coupled with an 'easy read' mode in the browser (I haven't tried Safari in a long while,) might make for a pleasant experience.
Non of the popular browsers have a good Bookmark UI IMHO, which leads to inappropriate tab use.
But seriously, you're right that the challenge is in actually designing a good UX for yourself. You've got four months to mimic Reader if that's what you want to do. I'd suggest XSLT, since RSS actually predates JSON, it's so old. That doesn't allow for any potential mistakes by RSS creators, though, which might be hairy. /shrug