The opportunity is not just open to Bayer Leverkusen only but to every other teams in the league which is what is raising the dust about Leverkusen going through an early defeat for a team that had an unbeaten streak all throughout the last season. Fair enough to say that they may not be able to repeat an unbeaten streak as it were but basically the early defeat just at the start of the season can affect their winning mentality.
However, I do agree with you that the season is still fresh and there's a much window of opportunity for the Xabi Alonso side to restrategize, not putting their guard down in order that they may prevail because it's really a challenging season as other teams ain't smiling which we will be seeing many surprising results this season in the Bundesliga.
there will definitely be many surprises, the Bundesliga has only been running for 2 more and that doesn't determine everything. but the strong competition will definitely be the teams that we can actually predict. like Union Berlin which as usual performed quite well at the beginning of the season and experienced a decline when the middle of the season started. several seasons their performance was quite good competing at least in the top 5 standings. but last season was very bad for Union Berlin.
maybe we will see a clearer mapping for our favorite teams when the season enters the middle of the season. I don't think this season will be easy enough for Leverkusen or Munich.