Many reports of people getting miles they shouldn't have gotten, or more miles than they deserved, when they were rerouted and rebooked. It can be faster for an agent to rebook in the default class for the cabin than to look up the original fare class and enter it.

It's hard to make this happen. If your schedule is flexible, the airline has enough flights on your route, and you checked that they're not full, you might try either getting to the airport early and standing by for an earlier flight, or missing yours by a bit (the "flat tire rule" usually gives you two hours) and standing by for a later one. It might work.

Agents tend to use the default fare class more when they're in a hurry, as when they have to rebook a packed 777. They're more likely to go through the full process when their workload is lighter, as it would be here. Still, it doesn't look like anything else gives you even a remote shot at miles.