I think Dortmund will hand Leverkusen their first defeat of the season. That would really hurt because there would only be 5 games left at that point. In fact, whatever the result will not change the fact that Leverkusen is the Bundesliga champion this season. But ending the league as champions with an unbeaten record would be history that will never be forgotten in football. I'm sure Alonso is also motivated to get an unbeaten record. Currently there are 4 matches left and there are several strong teams they will face. I think VfB and Frankfurt will be a challenge for them to maintain their unbeaten record.
I think Leverkusen will continue to play very well and play matches with its main squad in order to break this record in the Bundesliga. Every team playing against Leverkusen will have a hard time, but Dortmund must be very unhappy to miss the victory they came so close to because they were the closest team to beat Leverkusen. After the goal they conceded in extra time, Bayer Leverkusen will continue their efforts to maintain the record.
There are two competitions right now in which Dortmund has to concentrate properly. First is the Bundesliga and second is the Champions League competition. I am not saying this in any sequence where one is more important than the other. First of all, they have to win against Leipzig in the match which is going to be played on 27 April. Secondly, they will also have to properly concentrate on the match in the Champions League which is going to be played on 2 May. They have to aim for a win in both of those matches.
Maybe they can try to get a win in the Bundesliga match and aim for a draw as the Champions League match is going to be played in two legs. But I don't think that is going to be the best decision. They are already going up against a very hungry PSG team in the Champions League. So they cannot give any chance to PSG.