In any case, the assumption that a company with multiple revenue streams will just "run out of money" after 18 months...
It's easier than you think. Remember the layoffs in March?
... when they've more than tripled their initial Kickstarter goals, isn't a sound one.
The KS goal is a meaningless and random number. In a world of 10-20 mil budgets and sky-high costs of running studios like Obsidian (Feargus: "Our burn rate is $1 million a month"), 1 mil goal isn't much. Sure, they got 3.7 mil, but that's on paper. After KS takes their cut and the cost of merchandise is subtracted, they'll probably have 2.6-2.8 mil. A fortune for average Joe, a pittance for a studio.
As for the multiple revenue streams, what are they? Bethesda fucked Obsidian with NV - no royalties there. I doubt they get much from NWN2 sales. Not sure about AP and DS3. South Park's delayed, but I don't think it means more money for Obsidian due to THQ's bad financial state. What else do they have in development?