There may be witnesses in the Senate trial of the impeached POTUS* due to the possibility of four GOP senators who may vote in favor.
Remember that it's about testimony (and documents), not about Bolton
Washington — The White House is preparing for some Republican senators to join Democrats in voting to call witnesses in President Trump's impeachment trial, which could get underway in the coming days.
Senior White House officials tell CBS News they increasingly believe that at least four Republicans, and likely more, will vote to call witnesses. In addition to Senators Lisa Murkowski of Alaska, Susan Collins of Maine, Mitt Romney of Utah and possibly Cory Gardner of Colorado, the White House also views Rand Paul of Kentucky as a "wild card" and Senator Lamar Alexander of Tennessee as an "institutionalist" who might vote to call witnesses, as one official put it.
www.cbsnews.com/...
The problem of Bolton having new information is that its newness may not change the trial’s outcome, only the sales of his book.