This year you shouldn't have much of a problem, if you are an experienced hiker. I've seen hikers stop and quake at a easy rock hop, though, but for most, the JMT is a freeway. There'd be lots of complaints if there was much difficulty. But watch out for side trips. The Taboose Pass Trail, say, is often inundated at creek crossings, necessitating fords. Same with some other side trails.
And watch out for frozen snow on the north sides of the high passes. Early in the morning, a slip can kill you. Use an ice axe if you have one. Crampons might even be useful.
Have fun, but be safe!