Well, this is something. NFL Network reporter Mike Garafolo is reporting safety L.J. McCray failed a physical with the Seattle Seahawks, and the trade between Seattle and the 49ers has been voided. McCray reverts back to San Francisco, and the conditional 2018 seventh round pick goes back to the Seahawks.
The 49ers have 53 players on their roster, so this would seem to mean they need to either cut McCray or cut another player. If they were to waive McCray, given the failed physical, they would likely have to use the waived/injured designation. He would then revert to IR if he passes through waivers. The team could then agree with him on an injury settlement.
The 49ers will likely make some kind of announcement on this later today or tomorrow. McCray tore his ACL last year, but was back on the field the last two preseason games. This is certainly an interesting development for the 49ers.