Ash vs. Kotetsu (fourth round) will be the Top 16 round, since the Top 64 round was counted as the "second round" in the anime.
Ash vs. Virgil, the round in which Ash will most likely lose in, will probably be Top 8. The writers usually include two full battles for Ash in each league competition (Kanto and Hoenn were the exceptions).
Since there isn't any news, we'll just assume that Ash will lose to any pre-Gen 6 pokemon in this tournament, most likely Virgil and his Eevee due to the airdate differences between the most currently revealed episode (December 20, 2012) and the start of the new arc (January 17, 2012). Assuming a break and no two-episode specials, there are only two more episodes left of the tournament after the start of Ash vs. Kotetsu. I can't see Ash beating Virgil here.
Also, preview summaries of this new arc and the new dub season title confirm that Ash and co. will still be in the Unova region after the end of the league.