Season 1 definitly won't end that way, concidering tha scene is not mentioned again after the first chapter in manga. In fact, it's only mentioned twice. The very beginning of manga, and when Sakura has those flashes of images while standing in the balcony of her room.* (This happened in manga, didn't happen in the anime).
*here's the scan:
http://img.photobucket.com/albums/v149/Ellanalida/tsubasa01_c001_39.pngSo no, it hasn't been explained in the manga yet. But my theory is that in that scene, Sakura and Syaoran were captured by Fei Wong Reed (the bad guy).... I think it will be an actual event, and not a symbolic thing. If you look at the scan above, you see the country Fai came from, the country Kurogane came from, Fei Wong Reed's mark, the tsubasa symbol in the ruins, tsubasa, and scenes from the beginning of the manga/anime. All except the scenes from the beginning of the manga/anime has already "appeared".. So I think because of powers that Sakura has, she was able to see flashes of future. And that future, includes that beginning scene.