Got this email from Mileage Plus, seems to indicate dynamic pricing for awards starting in November 2017:
Introducing Everyday Awards.
Since you're a valued United MileagePlus® member, we'd like to share details with you about Everyday Awards, a new award travel option that will be available for bookings made on or after November 1, 2017.
Everyday Awards will replace Standard Awards, and prices will vary from flight to flight. While prices will fluctuate, we'll publish an award chart for Everyday Awards so that you'll know the highest number of miles needed for each award.
We'll also introduce an updated award chart for Saver Awards booked on or after November 1, 2017. With this updated Saver Award chart, you'll notice that select routes will have pricing changes, which may be higher or lower than today. However, there will be no pricing changes for Economy Saver Award travel to, from or within the 48 contiguous United States.
Here's the link that the "Learn More" button takes you to:
http://mileageplusupdates.com/mileag...nglish/awards/