IMO...

the "easy" part is over. To get the 500 miles, you needed 3 days of caps, of 1 day of Fridge Packs. That's well within the attention span of most people, and/or the eBay sellers. To get 1500 miles, you need 8 days of caps, or 3 days of Fridge Packs. That's starting to require some good attention span. I'd guess that the easy-players have now found the quick-redemption gone, and they might not want to put in the 8 days to get the 1500 miles. And defintely not the 27 days (caps) for 5000 miles.

I strongly suspect we'll see 500 miles back before the end of the year... but when they appear, you better grab them, as they'll probably go fast.

Steve B.