I tested this out with NodeCore, and while the resulting worlds it created are probably mostlly unplayable, it was fun to see some surreal results. There were worlds that were extremely radioactive, some that rapidly caught fire, some that were covered in dungeon stone, and some where pumwater was seeping out of every crevice. There were a lot of wet cement beaches, and trees made out of doors, and grassy fields transformed into a cornucopia of different ores and stones.
The method used to determine which nodes can substitute or be substituted uses a heuristic, so it works with every game ... but it's obvious it was only tested on a couple of games so far, as it misses a number of things; I'm pretty sure that liquids were not intended to be substituted for non-liquids, but not all liquids use the liquid drawtypes. The shuffle is also uniform-random, and ignores the relative rarity of some things (which is at least partly the point of the randomizer) but making extremely rare things become extremely common may cause some performance issues. Fine-tuning the heuristic with some more cross-game testing may help, and in extreme cases, maybe just white/black-listing certain problem cases that slip past the heuristic.
One feature that I'd love to see would be different randomization "zones" with different shuffles, maybe of configurable size...
There is a minor bug wherein tree leaves can be mostly substituted but occasionally some unsubstituted leaves are found at mapchunk boundaries. This is due to a limitation in how the engine works that would probably be difficult to fix without creating other issues.
N.B. make sure the mod is enabled before first creating the world, or else the first areas that generate will not be randomized. If you make a mistake on first startup, you can reset the world but keep the same seed by quitting, deleting map.sqlite, and restarting.