Oh, they're working on spicy stuff already:
View attachment 106784
AFAIK this was an experiment to test different hypersonic glider design by dropping them from high altitude balloon, but given what happened in recent days it's certainly an evocative image.
Other than China, the US is also exploring ways to deploy munitions and drones from high-altitude balloons in the warzones:
Imagine in times of war, China release tens or hundreds of these balloons and have them float to be near/over enemy-held territories, and have them release Shahed-like loitering munitions/kamikaze drones towards their designated targets below using swarming drone tactics. That's going be a sight to behold...
Now that we know the usefulness of high-altitude balloons (and high-altitude loitering UAVs in general) for national defense, including for offensive (launching munitions) and non-offensive (ISR) usages, I do expect that major powers would be looking into ways to deploying and countering these high-altitude balloon-based military platforms.
Recall that the US tested an airborne laser weapon system mounted onboard a modified Boeing 747 in the 2000s, i.e. Boeing YAL-1:

The laser was mounted at the nose of the aircraft. The laser platform's purpose is to become an airborne missile defense system to destroy tactical ballistic missiles at boost phase.

However, due to the high costs incured by the program and the impracticality due to the need for the platform to fly inside enemy territory to intercept enemy ballistic missiles, this project was eventually shelved in 2011.
Meanwhile, I think it's time for China to come up with solutions that can effectively deal with these kinds of threats at affordable costs.
As of now, both the US and China are already well in progress of developing newer airborne lasers that can be mounted on current and next-generation warplanes in the future, including both combat and non-combat warplanes.

In fact, Lockheed Martin, Boeing and Northrop Grumman have jointly delivered a high-energy laser weapon (LANCE) that can be carried by aircraft in podded form to the USAF for testing and evaluation in July last year:
Of course, this airborne laser weapon should be useful for not just intercepting enemy AAMs and SAMs, but also target enemy warplanes and drones in the future. In retrospect, military-purposed high-altitude balloons and high-altitude loitering UAVs in general can be targeted as well, such as this high-altitude loitering UAV airship:
As a sidenote, the famous PLA military hardware 3d-modeller @大包CG on Weibo made this Chinese counterpart to the Boeing YAL-1 by mounting an airborne laser system on a Y-20 to mock the panicking Americans:
