Could be, but I think that Chaos Legion would be great for a baseline-set that won't rotate out of Modern. It's ideal to start out with since it's the cheapest set, and at least in Bronze League you can have a lot of fun with only Chaos and the Rebellion Soulbound, without spending too much money. To really compete, one would need the Rebellion Set since a lot of great cards are in there. I'm thinking up a proposal and will post that hopefully next week and see what people think and where the flaws in my thinking are :-D