I think this is ultimately demonstrating that the War Powers Act is toothless. What's SCOTUS ultimately going to do? Even if they rule the war is illegal (quite a hope), they're not going to order troops who are actively under fire to stand down. They're not going to order actively deployed US troops to retreat from the combat zone, leaving troops in a situation where they have contradicting orders during an active shooting war.

At best, they would issue a ruling saying the war is illegal and ordering the president to end the war as quickly as possible. At which point, Trump would respond saying, "that's exactly what I was already doing." And ultimately nothing would change.