I don't think the Summoner Spell Swap Keystone will be taken very much

With it being in the Inspiration tree, you have to give up a lot of direct power just to have this. So if you end up taking this you will miss out on a number of other offensive/defensive runes for your main path. Leaving only your secondary path to have these things. Also the thing about an entire team swapping to smite means that all 5 players have made themselves weaker overall just to do this.

So while on paper it sounds utter broken, in practice I feel it won't have that great of an impact unless someone is confident enough in their champ to not have need for the most likely better runes for that champ.