Comey's post points to this post, it is about "Miracles". 8647 coincides with days from 911. The 86 is separated slightly from 47, so it can be taken as "remove or get rid of" 47. But the 8, 6, and 47 are made from 3 distinct materials, which denotes distinct entities of the message. A possible decode of the 8 tan sand shells, 6 rocks, and slate 47 is: Tonight send shells, rock 6 o'clock, slated for 47. One consideration is that, if there was an assassination attempt and a few days later we looked at his post, what would have been the ramifications psychologically? Another 911 event predicted?
Was Trump's Middle East trip all planned by black hats? It took 100 days for PDJT to get 2 trillion in investments, yet in a few days he stated that he got 10 trillion in new investments. Was everything made easy for him because they knew that he would be shelled if he went to peace talks in Turkey and all contracts would be nullified? Usually a POTUS first visits are with NATO EU allies, was 10 trillion the enticement? So question remains was this all a DS plan, part of the Q plan, or was Comey pointing to something entirely different related to "Miracles and 911"? Only PDJT can answer this with BDT.
It is better to take precautions and be called paranoid, then to take no heed.