Wembley Stadium will be a historic stadium for Dortmund if they win the match against Real Madrid. Dortmund won their first title in the 1996-1997 season when they beat Juventus in the final, while Dortmund failed in their last final in the 2012-2013 season when they were defeated by Bayern Munich. Uniquely, Dortmund failed at Wembley Stadium from Bayern Munich, but at that time Dortmund advanced to the final after beating Real Madrid in the semifinals with an aggregate of 4-3.
Dortmund will try their best to win their second Champions League title rather than let Real Madrid easily win their 15th title. I'm not sure Dortmund can win a game that many people don't consider them favorites, but anything can happen.
I think that the international final is eventually more exciting to fans than a German - German final. Finalist is finalist, yes, but it still is somehow different when a team wins against Real Madrid, while themselves being a team from the Bundesliga that is not called Bayern. As there has been a final already between Dortmund and Bayern, I think this is about the best outcome for everyone. I hope it will be fun to watch and Real doesn't kill Dortmund in the first 20 minutes.