We finally found a workaround!
This is only for deal level:
We trigger a deal based workflow by using "at least one associated contact has now in sequence equal to true" - then you can set the delay with the amount of days how long your sequence usually lasts. Afterwards you use the same, this time with false: "at least one associated contact has now in sequence equal to false".
Then we set a pre-defined property which is doing the rest (e.g. you have another small workflows which moves the deal then to another pipeline/triggers a task or whatever you want.)