Well, this is not going to stop to release new versions of HFW/HEN/CFW for 4.89... is mostly a problem for the custom .rco files released before
I dont want to trigger the alarms yet (because im not sure if there is some easy way to solve it) but is a big problem, in plain words...
Half of the .rco files from 4.89 are incompatibles with the custom rco files that was compatibles with 4.88
And the percentage of "broken" rco's probably is way higher than half of them, because a single rco file could store tenths of values inside the layout.txt files... if only one of them is broken we should consider the whole .rco file is broken
As example... the only rco mods i know for sure that are not broken are the ones for custom_render_plugin.rco there is a changelog where it can be seen at which line inside the layout.txt files is storing his values:
https://www.psdevwiki.com/ps3/Custom_render_plugin
It stores 6 values, located consecutivelly at lines:
664+1
665+1
666+1
667+1
668+1
669+1
The displacement in the 4.89 layout.txt files happened at line 2580, this is why custom_render_plugin.rco has not been updated (it stores his values before the displacement)
Actually... the best way to know how many rco files are incompatibles with the layout.txt from 4.88 is to extract the contents of 4.88 and 4.89 and compare the MD5 of all the rco files
If the MD5 matches it means the rco mods released for 4.88 of that specific rco file are compatibles with 4.89
Otherway (if the MD5 is different) there is a huge probability that the rco mods published before (compatibles with 4.88) are going to be broken in 4.89