Alex, Nike 10K is not a good race for PB. It has only 1 start for all 10K runners this year, that means the congestion could be even worst than previous. If you cannot go to the front earlier, your start could be very slow for up to 1-2Ks. There's lot of 10K races better than Nike to create PB.
After that I focused on training Half Marathon so I didn't run any 10K race (for the training runs I did make several sub50 run but it should be above 47min) . So far a year after I could push my 10K PB from mid 50min to late 40 given different running place.
In my case, it is already difficult enough to reach sub50 in one year... just thanks to good air quality in Australia ... and obviously I did put much effort this year..
so for me it is not a realistic goal to set sub40 as my next year goal... rather realistic for me to set it as my LIFE goal.