What I would like to see for new products isn't a World Champion Deck. I think it worked better for Netrunner, because there were 2 decks that could be played against each other.
For L5R, I'd rather see 7 Best of Clan decks (from the player from each clan that got the furthest at Worlds). They could function like intro decks, but they'd offer explicitly competent decks. No deck would contain cards not found in previous packs, so there would be no additional need to collect them all, but they could feature several (say 7 or so) alt-art cards per pack. If the cards chosen for alt-art weren't full playsets in the deck, I'd suggest adding playsets to the packs for completionists.
You could go further and add cards to make them role neutral (so they could be played at all tournaments), although I wouldn't think that would work particularly well as decks are built with those limitations & bonuses in mind.
As I said earlier, complete L5R decks would probably be $20USD. They could feature a write-up by their players or the card team detailing what strengths and limitations the deck has and how it best played.
I think that would bridge the gap between core set and full rotation. They would sell them for 12 months and then switch to the next year's decks.