Seeing Leipzig in the top 4 is normal and I am happy that this team does not lose its consistency every season. However, sometimes there are things that will prevent them from maintaining that position and Wolfsburg will indeed be quite a difficult opponent to beat. But in general, Leipzig can handle it and will continue to keep their distance from Dortmund's pursuit. The season is still long and I see it as just normal competition in the Bundesliga and maybe if Leipzig slips up, Dortmund will make good use of this to shift their position from the top 4.
A biggest surprise in this season is Bayer Leverkusen as they are improving more from the past season and currently stays at a first position with 31 points, 2 points more than Bayern Munich. It's no other word than very impressive performance from them.
Another surprise is Stuttgart as they have a first season in top range of Bundesliga after many years. Leipzig at least have been regularly appearing in top range of Bundesliga recent seasons. Their performance in this season is good especially after they sold their most important defender, Gvardiol to Manchester City in the summer transfer season. Without the Croatian defender, they still maintain a strong defense system with only 18 conceded goals in Bundesliga. About this conceded goal aspect, Stuttgart is a big surprise with only 15 conceded goals so far and it is a basement for their success so far.
Leverkusen and Stuttgart have appeared impressive so far this season and they are even competing at the top with defending champions Bayern Munich. Everyone really praised Leverkusen's performance, which was led directly by Xabi Alonso and made them one of the unbeaten teams in the Bundesliga. Stuttgart, which usually sits in the relegation zone, has made real improvements this season and we can see that their performance is also very stable and last time they managed to beat Dortmund.
The fact that they lose players every season does not make Leipzig lose their routine to compete at the top and they can maximize this with the existing squad. They may have lost one of their talented defenders this season but at least they still appear consistent among other teams. The competition is still open and the point difference is not that big, whoever and whenever will make the Bundesliga more interesting with the existing changes.