Let's be real here, most champions so far that had versus events have some sort of rivalry or grudge against each other in a past, swain and irelia are no different, as we saw in the irelia rework tailer, and we know irelia cut of swain's left hand. The skin ideas are: Archblade Irelia Fiendwing Swain
Nah. The Vs Event isn't necessarily about the champions but rather what each represent in the "Vs Universe". Swain isn't a rival to Irelia, neither the other way around.
vs 
. Those two would make a lot more sense.
vs 
. Volibear would need to be reworked first.
vs 
. The apex of rivalry.
Ideally, you'd have two champions from the same lane/role. Only Nasus vs Renekton fit that criteria (from the ones I mentioned).
They could go a step further and play on rivarly of theme instead. For example:
vs 
Fire vs Ice
vs 
Light vs Shadow
vs 
Creation vs Destruction (The Void)
vs 
Life vs Death
vs 
Brain vs Brawn
...
The options are many, but I don't think Irelia vs Swain is one of them. ######I left out Morgana vs Kayle because I don't know what they have in mind for their story, but those two are the "super obvious" choice.
Finally, they chose champions with potential for huge sales. Irelia might, but I don't think Swain will. Maybe I'm wrong, but I'm willing to bet one of the combinations I mentioned would sell a lot more than those two. Can you guess which one?
