One of the authors changed idea before submitting paper I have just finished a paper together with a number of colleagues and collaborators from other universities.
We were about to submit it but one of the authors does not agree anymore. His explanation is that, while he thinks the paper is fine, he has a new idea and does not want to publish this as it would make his idea ‘‘less original’’ (because some parts of his idea are already in this paper).
Mind that it would be difficult to  include his idea in the paper as while the methods are the same, the applications are totally different.
What would you do in this case?
I am the main contributor and another professor had the idea. He wants to cut out some other authors, including the professor who had the idea. He’s quite a powerful and famous academic though, that’s why I think he’s feeling entitled to do so.
Talk to the other collaborators who probably agree with you, and then take a unified front to tell him that holding several collaborators hostage is not ok.
Additionally, if part of his new publication uses a jointly developed idea which he intends to publish alone while blocking your joint work (that should be in the references of his planned solo paper), then this strikes me as borderline plagiarism. In any case, it’s very bad form.