Count me as still on the skeptical side when it comes to trading Freddy. There's a bit of an incongruency between the three teams you mention as being most interested in Freddy and the Brewers' asking price, which you describe as "greater than for Burnes".
First of all, the farm systems of those three teams all stink. Like consensus bottom 5 in baseball sort of stink. The only major league ready prospect that I'd have interest in is JR Ritchie, and why wouldn't the Braves just keep him and use him in their rotation instead of trading him for a one year rental in Freddy. Which means most, if not all of the value coming back to the Brewers in a Freddy trade is controllable pieces from their major league rosters.
All of the Braves' controllable pieces are signed to contract extensions, which makes them more expensive. The only exception is Drake Baldwin and while we do need to start planning for life after William, I don't see them making him available. I will say Michael Harris is interesting from a Brewers perspective given his extension is on the cheaper side and he's still only 24.
As for the Astros and Padres, seriously who is out there that makes a deal worthwhile Brewers? It's all aging, expensive vets, expiring contracts, and a steaming pile of yuck.