If Bayern Munich doesn't manage to get a new striker for next season, Bayern Munich will not only have difficulties in the Champions League, but Bayern Munich may also have difficulties in the Bundesliga because other teams like Dortmund can also be strong next season even though for now Dortmund looks like not taken into account by many people. So Thomas Tuchel's own task for now is still very much because apart from having to be able to find better front-line players, Thomas Tuchel must also be able to make Bayern Munich stronger next season with the existing players.
I think it's the other way around if Bayern Munich doesn't get a pure striker next season then they will have more difficulty competing in the champions league than the bundesliga. We know that with very even players at Bayern Munich and only lacking a finisher in front of goal they still won the Bundesliga last season, yes although everyone knows they had a very dramatic final. But what is clear is that a striker will still be needed by Bayern Munich regardless of any competition and with very good finances they should be able to do it.