Monero's (dynamic) fee structure is very depending on the dynamic block size and the other way round and all changes have to be very carefully evaluated since otherwise the penalty algo for miners increasing block size might get obsolete.
For now, in the v7 upgrade (Monero 0.12) there has been just a quick fix implemented choosing low priority, so 0.25x of the standard fee if these criteria match:
- there's no backlog in the tx pool for the low priority fee level
- the last N (=10) blocks are not 'almost full' (>80%) (estimated by summing up the last N block sizes and dividing it by N times the current full reward zone)
There were no changes made to the constants per kB in this release and the fee structure is meant to be evaluated for the September hard fork along with Bulletproofs, which will be released if there is no serious flaw found during the currently ongoing external audits.