There's no doubt that Amazon has much more established delivery logistics than Uber at this point, but I wonder if the real value would come from another angle:

Uber has been pushing hard on self-driving cars (I mean, in the long term, it strikes me as their only viable business model, so it makes sense). By my best estimates, salary for delivery drivers for Amazon packages run somewhere between $6B and $10B per year (for comparison, if I remember correctly, Amazon's revenue is somewhere around $35B/yr). Automating delivery could be a HUGE deal for them, and an opportunity to scoop up a major player in the autonomous driving space might look very appealing.

Then again, with Washington State throwing the doors open for autonomous testing, Amazon could likely develop their own system on their own turf for less, even if Uber's valuation goes WAY down.

At this point, sure. In all likelihood, the actual operating business is more fairly priced in a fire sale. Free up overhead by trimming down the "eat the world" grandiose plans, cut growth-for-the-sake-of-fundraising subsidies, add some haircuts on bondholders, and you've got something that will reasonably work.