Don't know if this will be a criteria for future VS skins but.....

The current vs pairs share the same Sub-classes vs: skirmisher now vs :juggernauts a lot of people(myself included) have a whole bunch of league rivals we want to see as vs skins for next year but if it'll only be for well known rivals the share Sub-classes then there only one pair of rivals left that fit this criteria:vs which make thematic sense cause rivals should be be able to match each other in battle. but i could be wrong and riot just picks whichever grudge matches would be good for the vs theme