I still insist that while game 1 it may be a negative, post-board the ability to find more exact answers for different archetypes will make the deck stronger. If I can have Surgical every game 2 against Phoenix, then I'll be happy.
That being said, I still understand each deck gets to have better hands, which means linear archetypes will be able to find ways to get around hate and be better against the strategy also, but I think this just leads to better games of magic rewarding better play. I think the mulligan change won't affect the deck that much for that reason. Rock has always been a stable archetype, and I don't think the new mulligan would change its position very much.