Route #3: Giving up a good prospect while not paying any money
This is the least likely option in my mind. After working so hard to rebuild a farm system that was lacking in high-end prospects, John Mozeliak won't be keen on selling from said farm system. In fact, Mo worked hard to not give up a top prospect this past trade deadline when he was able to land one of the best available starting pitchers.
Therefore, packaging a high-end prospect with Mikolas, a pricey, underperforming veteran, probably won't be the path that the front office chooses. These types of trades are done quite frequently in baseball. This past offseason, the Atlanta Braves traded for Marco Gonzalez, Evan White, and Jarred Kelenic. The Braves promptly traded Gonzalez to the Pirates with cash, and Evan White was also traded to the Los Angeles Angels for a pair of veteran players.
The Atlanta Braves also made a similar trade in 2015 when they acquired Bronson Arroyo and former top prospect Touki Toussant. This is the epitome of these types of deals. The Braves took on an expensive veteran and a top prospect while also not asking for money in return from the Arizona Diamondbacks. Arroyo was released from the Braves without throwing a single pitch for them.
The benefit of this type of trade is that it opens up the number of teams willing to make this deal. Every organization in baseball covets young, cheap, and talented players regardless of their competitive window. Mozeliak will just need to find a team willing to eat some salary to receive a top organizational prospect.
Teams who could be willing to do this would once again be the Atlanta Braves, Boston Red Sox, Los Angeles Angels, Houston Astros, and possibly even the Texas Rangers. These are all organizations that boast high payrolls with a creative front office. Additionally, their farm systems are relatively weak, so they could benefit from some prospect infusion.
If this is the desired route of the front office, there is no safe prospect in a deal. Tink Hence, Thomas Saggese, Quinn Mathews, and possibly even Jordan Walker could all be called for by the opposing team.