The pundits speculate (and Trump can hint) that the President’s “Cohen problem” can be solved rather quickly with a Presidential pardon. As usual with Trump — his vision is clouded by wishful thinking.
The truth is that a pardon simply means that Cohen has a free pass for conducting federal crimes. However — a pardon for Cohen does not automatically void the warrant that allowed investigators to seize a truckload of papers, hard drives and video/audio records.
Even if Cohen's pardon from trump extends to possible contempt of court (for refusing to testify), the seized documents still speak for themselves. The toothpaste is out of the tube, and pardoning Cohen does not put it back in.
The talking heads are now saying their Whitehouse sources tell them that Trump's legal team is more worried about the "Cohen problem" than the main Mueller investigation. Perhaps this is because even if Cohen doesn't "flip," there is evidence in the files that stands on its own and speaks for itself.